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[Xen-devel] [PATCH for-next 3/6] xen/vpci: introduce basic handlers to trap accesses to the PCI config space



This functionality is going to reside in vpci.c (and the corresponding vpci.h
header), and should be arch-agnostic. The handlers introduced in this patch
setup the basic functionality required in order to trap accesses to the PCI
config space, and allow decoding the address and finding the corresponding
handler that should handle the access (although no handlers are implemented).

Note that the traps to the PCI IO ports registers (0xcf8/0xcfc) are setup
inside of a x86 HVM file, since that's not shared with other arches.

A new XEN_X86_EMU_VPCI x86 domain flag is added in order to signal Xen whether
a domain should use the newly introduced vPCI handlers, this is only enabled
for PVH Dom0 at the moment.

A very simple user-space test is also provided, so that the basic functionality
of the vPCI traps can be asserted. This has been proven quite helpful during
development, since the logic to handle partial accesses or accesses that expand
across multiple registers is not trivial.

The handlers for the registers are added to a red-black tree, that indexes them
based on their offset. Since Xen needs to handle partial accesses to the
registers and access that expand across multiple registers the logic in
xen_vpci_{read/write} is kind of convoluted, I've tried to properly comment it
in order to make it easier to understand.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
 .gitignore                        |   4 +
 tools/libxl/libxl_x86.c           |   2 +-
 tools/tests/Makefile              |   1 +
 tools/tests/vpci/Makefile         |  45 ++++
 tools/tests/vpci/emul.h           | 102 +++++++++
 tools/tests/vpci/main.c           | 206 ++++++++++++++++++
 xen/arch/arm/xen.lds.S            |   3 +
 xen/arch/x86/domain.c             |   3 +-
 xen/arch/x86/hvm/hvm.c            |   2 +
 xen/arch/x86/hvm/io.c             | 118 ++++++++++
 xen/arch/x86/setup.c              |   3 +-
 xen/arch/x86/xen.lds.S            |   3 +
 xen/drivers/Makefile              |   2 +-
 xen/drivers/passthrough/pci.c     |   3 +
 xen/drivers/vpci/Makefile         |   1 +
 xen/drivers/vpci/vpci.c           | 446 ++++++++++++++++++++++++++++++++++++++
 xen/include/asm-x86/domain.h      |   1 +
 xen/include/asm-x86/hvm/io.h      |   3 +
 xen/include/public/arch-x86/xen.h |   5 +-
 xen/include/xen/pci.h             |   4 +
 xen/include/xen/vpci.h            |  62 ++++++
 21 files changed, 1014 insertions(+), 5 deletions(-)
 create mode 100644 tools/tests/vpci/Makefile
 create mode 100644 tools/tests/vpci/emul.h
 create mode 100644 tools/tests/vpci/main.c
 create mode 100644 xen/drivers/vpci/Makefile
 create mode 100644 xen/drivers/vpci/vpci.c
 create mode 100644 xen/include/xen/vpci.h

diff --git a/.gitignore b/.gitignore
index 74747cb7e7..ebafba25b5 100644
--- a/.gitignore
+++ b/.gitignore
@@ -236,6 +236,10 @@ tools/tests/regression/build/*
 tools/tests/regression/downloads/*
 tools/tests/mem-sharing/memshrtool
 tools/tests/mce-test/tools/xen-mceinj
+tools/tests/vpci/rbtree.[hc]
+tools/tests/vpci/vpci.[hc]
+tools/tests/vpci/test_vpci.out
+tools/tests/vpci/test_vpci
 tools/xcutils/lsevtchn
 tools/xcutils/readnotes
 tools/xenbackendd/_paths.h
diff --git a/tools/libxl/libxl_x86.c b/tools/libxl/libxl_x86.c
index 455f6f0bed..dd7fc78a99 100644
--- a/tools/libxl/libxl_x86.c
+++ b/tools/libxl/libxl_x86.c
@@ -11,7 +11,7 @@ int libxl__arch_domain_prepare_config(libxl__gc *gc,
     if (d_config->c_info.type == LIBXL_DOMAIN_TYPE_HVM) {
         if (d_config->b_info.device_model_version !=
             LIBXL_DEVICE_MODEL_VERSION_NONE) {
-            xc_config->emulation_flags = XEN_X86_EMU_ALL;
+            xc_config->emulation_flags = (XEN_X86_EMU_ALL & ~XEN_X86_EMU_VPCI);
         } else if (libxl_defbool_val(d_config->b_info.u.hvm.apic)) {
             /*
              * HVM guests without device model may want
diff --git a/tools/tests/Makefile b/tools/tests/Makefile
index 639776130b..5cfe781e62 100644
--- a/tools/tests/Makefile
+++ b/tools/tests/Makefile
@@ -13,6 +13,7 @@ endif
 SUBDIRS-$(CONFIG_X86) += x86_emulator
 SUBDIRS-y += xen-access
 SUBDIRS-y += xenstore
+SUBDIRS-$(CONFIG_HAS_PCI) += vpci
 
 .PHONY: all clean install distclean
 all clean distclean: %: subdirs-%
diff --git a/tools/tests/vpci/Makefile b/tools/tests/vpci/Makefile
new file mode 100644
index 0000000000..7969fcbd82
--- /dev/null
+++ b/tools/tests/vpci/Makefile
@@ -0,0 +1,45 @@
+
+XEN_ROOT=$(CURDIR)/../../..
+include $(XEN_ROOT)/tools/Rules.mk
+
+TARGET := test_vpci
+
+.PHONY: all
+all: $(TARGET)
+
+.PHONY: run
+run: $(TARGET)
+       ./$(TARGET) > $(TARGET).out
+
+$(TARGET): vpci.c vpci.h rbtree.c rbtree.h
+       $(HOSTCC) -g -o $@ vpci.c main.c rbtree.c
+
+.PHONY: clean
+clean:
+       rm -rf $(TARGET) $(TARGET).out *.o *~ vpci.h vpci.c rbtree.c rbtree.h
+
+.PHONY: distclean
+distclean: clean
+
+.PHONY: install
+install:
+
+vpci.h: $(XEN_ROOT)/xen/include/xen/vpci.h
+       sed -e '/#include/d' <$< >$@
+
+vpci.c: $(XEN_ROOT)/xen/drivers/vpci/vpci.c
+       # Trick the compiler so it doesn't complain about missing symbols
+       sed -e '/#include/d' \
+           -e '1s;^;#include "emul.h"\
+                    const vpci_register_init_t __start_vpci_array[1]\;\
+                    const vpci_register_init_t __end_vpci_array[1]\;\
+                    ;' <$< >$@
+
+rbtree.h: $(XEN_ROOT)/xen/include/xen/rbtree.h
+       sed -e '/#include/d' <$< >$@
+
+rbtree.c: $(XEN_ROOT)/xen/common/rbtree.c
+       sed -e "/#include/d" \
+           -e '1s;^;#include "emul.h"\
+                    ;' <$< >$@
+
diff --git a/tools/tests/vpci/emul.h b/tools/tests/vpci/emul.h
new file mode 100644
index 0000000000..c090b6d6aa
--- /dev/null
+++ b/tools/tests/vpci/emul.h
@@ -0,0 +1,102 @@
+/*
+ * Unit tests for the generic vPCI handler code.
+ *
+ * Copyright (C) 2017 Citrix Systems R&D
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms and conditions of the GNU General Public
+ * License, version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef _TEST_VPCI_
+#define _TEST_VPCI_
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdbool.h>
+#include <errno.h>
+#include <assert.h>
+
+#define container_of(ptr, type, member) ({                      \
+        typeof( ((type *)0)->member ) *__mptr = (ptr);          \
+        (type *)( (char *)__mptr - offsetof(type,member) );})
+
+#include "rbtree.h"
+
+struct pci_dev {
+    struct domain *domain;
+    struct vpci *vpci;
+};
+
+struct domain {
+    struct pci_dev pdev;
+};
+
+struct vcpu
+{
+    struct domain *domain;
+};
+
+extern struct vcpu v;
+#define current (&v)
+
+#define has_vpci(d) true
+
+#include "vpci.h"
+
+#define xzalloc(type) (type *)calloc(1, sizeof(type))
+#define xfree(p) free(p)
+
+#define EXPORT_SYMBOL(x)
+
+#define pci_get_pdev_by_domain(d, ...) &(d)->pdev
+
+#define atomic_read(x) 1
+
+/* Dummy native helpers. Writes are ignored, reads return 1's. */
+#define pci_conf_read8(...) (0xff)
+#define pci_conf_read16(...) (0xffff)
+#define pci_conf_read32(...) (0xffffffff)
+#define pci_conf_write8(...)
+#define pci_conf_write16(...)
+#define pci_conf_write32(...)
+
+#define BUG() assert(0)
+#define ASSERT_UNREACHABLE() assert(0)
+#define ASSERT(x) assert(x)
+
+#ifdef _LP64
+#define BITS_PER_LONG 64
+#else
+#define BITS_PER_LONG 32
+#endif
+#define GENMASK(h, l) \
+    (((~0UL) << (l)) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
+
+#define min(x,y) ({ \
+        const typeof(x) _x = (x);       \
+        const typeof(y) _y = (y);       \
+        (void) (&_x == &_y);            \
+        _x < _y ? _x : _y; })
+
+#endif
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
+
diff --git a/tools/tests/vpci/main.c b/tools/tests/vpci/main.c
new file mode 100644
index 0000000000..0fc63de038
--- /dev/null
+++ b/tools/tests/vpci/main.c
@@ -0,0 +1,206 @@
+/*
+ * Unit tests for the generic vPCI handler code.
+ *
+ * Copyright (C) 2017 Citrix Systems R&D
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms and conditions of the GNU General Public
+ * License, version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "emul.h"
+
+/* Single vcpu (current), and single domain with a single PCI device. */
+static struct vpci vpci = {
+    .handlers = RB_ROOT,
+};
+
+static struct domain d = {
+    .pdev.domain = &d,
+    .pdev.vpci = &vpci,
+};
+
+struct vcpu v = { .domain = &d };
+
+/* Dummy hooks, write stores data, read fetches it. */
+static int vpci_read8(struct pci_dev *pdev, unsigned int reg,
+                      union vpci_val *val, void *data)
+{
+    uint8_t *priv = data;
+
+    val->half_word = *priv;
+    return 0;
+}
+
+static int vpci_write8(struct pci_dev *pdev, unsigned int reg,
+                       union vpci_val val, void *data)
+{
+    uint8_t *priv = data;
+
+    *priv = val.half_word;
+    return 0;
+}
+
+static int vpci_read16(struct pci_dev *pdev, unsigned int reg,
+                       union vpci_val *val, void *data)
+{
+    uint16_t *priv = data;
+
+    val->word = *priv;
+    return 0;
+}
+
+static int vpci_write16(struct pci_dev *pdev, unsigned int reg,
+                        union vpci_val val, void *data)
+{
+    uint16_t *priv = data;
+
+    *priv = val.word;
+    return 0;
+}
+
+static int vpci_read32(struct pci_dev *pdev, unsigned int reg,
+                       union vpci_val *val, void *data)
+{
+    uint32_t *priv = data;
+
+    val->double_word = *priv;
+    return 0;
+}
+
+static int vpci_write32(struct pci_dev *pdev, unsigned int reg,
+                        union vpci_val val, void *data)
+{
+    uint32_t *priv = data;
+
+    *priv = val.double_word;
+    return 0;
+}
+
+#define VPCI_READ(reg, size, data) \
+    assert(!xen_vpci_read(0, 0, 0, reg, size, data))
+
+#define VPCI_READ_CHECK(reg, size, expected) ({ \
+    uint32_t val;                               \
+    VPCI_READ(reg, size, &val);                 \
+    assert(val == expected);                    \
+    })
+
+#define VPCI_WRITE(reg, size, data) \
+    assert(!xen_vpci_write(0, 0, 0, reg, size, data))
+
+#define VPCI_CHECK_REG(reg, size, data) ({      \
+    VPCI_WRITE(reg, size, data);                \
+    VPCI_READ_CHECK(reg, size, data);           \
+    })
+
+#define VPCI_ADD_REG(fread, fwrite, off, size, store)                         \
+    assert(!xen_vpci_add_register(&d.pdev, fread, fwrite, off, size, &store)) \
+
+#define VPCI_ADD_INVALID_REG(fread, fwrite, off, size)                      \
+    assert(xen_vpci_add_register(&d.pdev, fread, fwrite, off, size, NULL))  \
+
+int
+main(int argc, char **argv)
+{
+    /* Index storage by offset. */
+    uint32_t r0 = 0xdeadbeef;
+    uint8_t r5 = 0xef;
+    uint8_t r6 = 0xbe;
+    uint8_t r7 = 0xef;
+    uint16_t r12 = 0x8696;
+    int rc;
+
+    VPCI_ADD_REG(vpci_read32, vpci_write32, 0, 4, r0);
+    VPCI_READ_CHECK(0, 4, 0xdeadbeef);
+    VPCI_CHECK_REG(0, 4, 0xbcbcbcbc);
+
+    VPCI_ADD_REG(vpci_read8, vpci_write8, 5, 1, r5);
+    VPCI_READ_CHECK(5, 1, 0xef);
+    VPCI_CHECK_REG(5, 1, 0xba);
+
+    VPCI_ADD_REG(vpci_read8, vpci_write8, 6, 1, r6);
+    VPCI_READ_CHECK(6, 1, 0xbe);
+    VPCI_CHECK_REG(6, 1, 0xba);
+
+    VPCI_ADD_REG(vpci_read8, vpci_write8, 7, 1, r7);
+    VPCI_READ_CHECK(7, 1, 0xef);
+    VPCI_CHECK_REG(7, 1, 0xbd);
+
+    VPCI_ADD_REG(vpci_read16, vpci_write16, 12, 2, r12);
+    VPCI_READ_CHECK(12, 2, 0x8696);
+    VPCI_READ_CHECK(12, 4, 0xffff8696);
+
+    /*
+     * At this point we have the following layout:
+     *
+     * 32    24    16     8     0
+     *  +-----+-----+-----+-----+
+     *  |          r0           | 0
+     *  +-----+-----+-----+-----+
+     *  | r7  |  r6 |  r5 |/////| 32
+     *  +-----+-----+-----+-----|
+     *  |///////////////////////| 64
+     *  +-----------+-----------+
+     *  |///////////|    r12    | 96
+     *  +-----------+-----------+
+     *             ...
+     *  / = empty.
+     */
+
+    /* Try to add an overlapping register handler. */
+    VPCI_ADD_INVALID_REG(vpci_read32, vpci_write32, 4, 4);
+
+    /* Try to add a non-aligned register. */
+    VPCI_ADD_INVALID_REG(vpci_read16, vpci_write16, 15, 2);
+
+    /* Try to add a register with wrong size. */
+    VPCI_ADD_INVALID_REG(vpci_read16, vpci_write16, 8, 3);
+
+    /* Try to add a register with missing handlers. */
+    VPCI_ADD_INVALID_REG(vpci_read16, NULL, 8, 2);
+    VPCI_ADD_INVALID_REG(NULL, vpci_write16, 8, 2);
+
+    /* Read/write of unset register. */
+    VPCI_READ_CHECK(8, 4, 0xffffffff);
+    VPCI_READ_CHECK(8, 2, 0xffff);
+    VPCI_READ_CHECK(8, 1, 0xff);
+    VPCI_WRITE(10, 2, 0xbeef);
+    VPCI_READ_CHECK(10, 2, 0xffff);
+
+    /* Read of multiple registers */
+    VPCI_CHECK_REG(7, 1, 0xbd);
+    VPCI_READ_CHECK(4, 4, 0xbdbabaff);
+
+    /* Partial read of a register. */
+    VPCI_CHECK_REG(0, 4, 0x1a1b1c1d);
+    VPCI_READ_CHECK(2, 1, 0x1b);
+    VPCI_READ_CHECK(6, 2, 0xbdba);
+
+    /* Write of multiple registers. */
+    VPCI_CHECK_REG(4, 4, 0xaabbccff);
+
+    /* Partial write of a register. */
+    VPCI_CHECK_REG(2, 1, 0xfe);
+    VPCI_CHECK_REG(6, 2, 0xfebc);
+
+    return 0;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
+
diff --git a/xen/arch/arm/xen.lds.S b/xen/arch/arm/xen.lds.S
index 44bd3bf0ce..41bf9dfaf3 100644
--- a/xen/arch/arm/xen.lds.S
+++ b/xen/arch/arm/xen.lds.S
@@ -79,6 +79,9 @@ SECTIONS
        __start_schedulers_array = .;
        *(.data.schedulers)
        __end_schedulers_array = .;
+       __start_vpci_array = .;
+       *(.data.vpci)
+       __end_vpci_array = .;
        *(.data.rel)
        *(.data.rel.*)
        CONSTRUCTORS
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 90e2b1f82a..d516b46f67 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -500,7 +500,8 @@ static bool emulation_flags_ok(const struct domain *d, 
uint32_t emflags)
     if ( is_hvm_domain(d) )
     {
         if ( is_hardware_domain(d) &&
-             emflags != (XEN_X86_EMU_LAPIC|XEN_X86_EMU_IOAPIC) )
+             emflags != (XEN_X86_EMU_LAPIC|XEN_X86_EMU_IOAPIC|
+                         XEN_X86_EMU_VPCI) )
             return false;
         if ( !is_hardware_domain(d) && emflags &&
              emflags != XEN_X86_EMU_ALL && emflags != XEN_X86_EMU_LAPIC )
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index f50d15ff50..c2a9b76a81 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -37,6 +37,7 @@
 #include <xen/vm_event.h>
 #include <xen/monitor.h>
 #include <xen/warning.h>
+#include <xen/vpci.h>
 #include <asm/shadow.h>
 #include <asm/hap.h>
 #include <asm/current.h>
@@ -655,6 +656,7 @@ int hvm_domain_initialise(struct domain *d)
         d->arch.hvm_domain.io_bitmap = hvm_io_bitmap;
 
     register_g2m_portio_handler(d);
+    register_vpci_portio_handler(d);
 
     hvm_ioreq_init(d);
 
diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index 9e004098cc..11d561e861 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -25,6 +25,7 @@
 #include <xen/trace.h>
 #include <xen/event.h>
 #include <xen/hypercall.h>
+#include <xen/vpci.h>
 #include <asm/current.h>
 #include <asm/cpufeature.h>
 #include <asm/processor.h>
@@ -257,6 +258,123 @@ void register_g2m_portio_handler(struct domain *d)
     handler->ops = &g2m_portio_ops;
 }
 
+/* Do some sanity checks. */
+static int vpci_access_check(unsigned int reg, unsigned int len)
+{
+    /* Check read size */
+    if ( len != 1 && len != 2 && len != 4 )
+    {
+        gdprintk(XENLOG_WARNING, "invalid length (reg: %#x, len: %u)\n",
+                 reg, len);
+        return -EINVAL;
+    }
+
+    /* Check offset alignment */
+    if ( reg & (len - 1) )
+    {
+        gdprintk(XENLOG_WARNING,
+                 "invalid access size alignment (reg: %#x, len: %u)\n",
+                 reg, len);
+        return -EINVAL;
+    }
+
+    return 0;
+}
+
+/* Helper to decode a PCI address. */
+static void vpci_decode_addr(unsigned int cf8, unsigned int addr,
+                             unsigned int *bus, unsigned int *devfn,
+                             unsigned int *reg)
+{
+    unsigned long bdf;
+
+    bdf = CF8_BDF(cf8);
+    *bus = PCI_BUS(bdf);
+    *devfn = PCI_DEVFN(PCI_SLOT(bdf), PCI_FUNC(bdf));
+    /*
+     * NB: the lower 2 bits of the register address are fetched from the
+     * offset into the 0xcfc register when reading/writing to it.
+     */
+    *reg = (cf8 & 0xfc) | (addr & 3);
+}
+
+/* vPCI config space IO ports handlers (0xcf8/0xcfc). */
+static bool_t vpci_portio_accept(const struct hvm_io_handler *handler,
+                                 const ioreq_t *p)
+{
+    return (p->addr == 0xcf8 && p->size == 4) || (p->addr & 0xfffc) == 0xcfc;
+}
+
+static int vpci_portio_read(const struct hvm_io_handler *handler,
+                            uint64_t addr, uint32_t size, uint64_t *data)
+{
+    struct domain *d = current->domain;
+    unsigned int bus, devfn, reg;
+    uint32_t data32;
+    int rc;
+
+    if ( addr == 0xcf8 )
+    {
+        ASSERT(size == 4);
+        *data = d->arch.hvm_domain.pci_cf8;
+        return X86EMUL_OKAY;
+    }
+
+    /* Decode the PCI address. */
+    vpci_decode_addr(d->arch.hvm_domain.pci_cf8, addr, &bus, &devfn, &reg);
+
+    if ( vpci_access_check(reg, size) || reg >= 0xff )
+        return X86EMUL_UNHANDLEABLE;
+
+    rc = xen_vpci_read(0, bus, devfn, reg, size, &data32);
+    if ( !rc )
+        *data = data32;
+
+     return rc ? X86EMUL_UNHANDLEABLE : X86EMUL_OKAY;
+}
+
+static int vpci_portio_write(const struct hvm_io_handler *handler,
+                             uint64_t addr, uint32_t size, uint64_t data)
+{
+    struct domain *d = current->domain;
+    unsigned int bus, devfn, reg;
+    int rc;
+
+    if ( addr == 0xcf8 )
+    {
+        ASSERT(size == 4);
+        d->arch.hvm_domain.pci_cf8 = data;
+        return X86EMUL_OKAY;
+    }
+
+    /* Decode the PCI address. */
+    vpci_decode_addr(d->arch.hvm_domain.pci_cf8, addr, &bus, &devfn, &reg);
+
+    if ( vpci_access_check(reg, size) || reg >= 0xff )
+        return X86EMUL_UNHANDLEABLE;
+
+    rc = xen_vpci_write(0, bus, devfn, reg, size, data);
+
+    return rc ? X86EMUL_UNHANDLEABLE : X86EMUL_OKAY;
+}
+
+static const struct hvm_io_ops vpci_portio_ops = {
+    .accept = vpci_portio_accept,
+    .read = vpci_portio_read,
+    .write = vpci_portio_write,
+};
+
+void register_vpci_portio_handler(struct domain *d)
+{
+    struct hvm_io_handler *handler = hvm_next_io_handler(d);
+
+    if ( !has_vpci(d) || handler == NULL )
+        return;
+
+    handler->type = IOREQ_TYPE_PIO;
+    handler->ops = &vpci_portio_ops;
+}
+
 /*
  * Local variables:
  * mode: C
diff --git a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
index c3d99e9b54..b4592311bf 100644
--- a/xen/arch/x86/setup.c
+++ b/xen/arch/x86/setup.c
@@ -1564,7 +1564,8 @@ void __init noreturn __start_xen(unsigned long mbi_p)
         domcr_flags |= DOMCRF_hvm |
                        ((hvm_funcs.hap_supported && !opt_dom0_shadow) ?
                          DOMCRF_hap : 0);
-        config.emulation_flags = XEN_X86_EMU_LAPIC|XEN_X86_EMU_IOAPIC;
+        config.emulation_flags = XEN_X86_EMU_LAPIC|XEN_X86_EMU_IOAPIC|
+                                 XEN_X86_EMU_VPCI;
     }
 
     /* Create initial domain 0. */
diff --git a/xen/arch/x86/xen.lds.S b/xen/arch/x86/xen.lds.S
index 8289a1bf09..f5cc8e2b8d 100644
--- a/xen/arch/x86/xen.lds.S
+++ b/xen/arch/x86/xen.lds.S
@@ -224,6 +224,9 @@ SECTIONS
        __start_schedulers_array = .;
        *(.data.schedulers)
        __end_schedulers_array = .;
+       __start_vpci_array = .;
+       *(.data.vpci)
+       __end_vpci_array = .;
        *(.data.rel.ro)
        *(.data.rel.ro.*)
   } :text
diff --git a/xen/drivers/Makefile b/xen/drivers/Makefile
index 19391802a8..d51c766453 100644
--- a/xen/drivers/Makefile
+++ b/xen/drivers/Makefile
@@ -1,6 +1,6 @@
 subdir-y += char
 subdir-$(CONFIG_HAS_CPUFREQ) += cpufreq
-subdir-$(CONFIG_HAS_PCI) += pci
+subdir-$(CONFIG_HAS_PCI) += pci vpci
 subdir-$(CONFIG_HAS_PASSTHROUGH) += passthrough
 subdir-$(CONFIG_ACPI) += acpi
 subdir-$(CONFIG_VIDEO) += video
diff --git a/xen/drivers/passthrough/pci.c b/xen/drivers/passthrough/pci.c
index 4e33442976..7710c41533 100644
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -30,6 +30,7 @@
 #include <xen/radix-tree.h>
 #include <xen/softirq.h>
 #include <xen/tasklet.h>
+#include <xen/vpci.h>
 #include <xsm/xsm.h>
 #include <asm/msi.h>
 #include "ats.h"
@@ -1061,6 +1062,8 @@ static void setup_one_hwdom_device(const struct 
setup_hwdom *ctxt,
         devfn += pdev->phantom_stride;
     } while ( devfn != pdev->devfn &&
               PCI_SLOT(devfn) == PCI_SLOT(pdev->devfn) );
+
+    xen_vpci_add_handlers(pdev);
 }
 
 static int __hwdom_init _setup_hwdom_pci_devices(struct pci_seg *pseg, void 
*arg)
diff --git a/xen/drivers/vpci/Makefile b/xen/drivers/vpci/Makefile
new file mode 100644
index 0000000000..840a906470
--- /dev/null
+++ b/xen/drivers/vpci/Makefile
@@ -0,0 +1 @@
+obj-y += vpci.o
diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
new file mode 100644
index 0000000000..8648de5899
--- /dev/null
+++ b/xen/drivers/vpci/vpci.c
@@ -0,0 +1,446 @@
+/*
+ * Generic functionality for handling accesses to the PCI configuration space
+ * from guests.
+ *
+ * Copyright (C) 2017 Citrix Systems R&D
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms and conditions of the GNU General Public
+ * License, version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <xen/sched.h>
+#include <xen/vpci.h>
+
+extern const vpci_register_init_t __start_vpci_array[], __end_vpci_array[];
+#define NUM_VPCI_INIT (__end_vpci_array - __start_vpci_array)
+#define vpci_init __start_vpci_array
+
+int xen_vpci_add_handlers(struct pci_dev *pdev)
+{
+    int i, rc = 0;
+
+    if ( !has_vpci(pdev->domain) )
+        return 0;
+
+    pdev->vpci = xzalloc(struct vpci);
+    if ( !pdev->vpci )
+        return -ENOMEM;
+
+    pdev->vpci->handlers = RB_ROOT;
+
+    for ( i = 0; i < NUM_VPCI_INIT; i++ )
+    {
+        rc = vpci_init[i](pdev);
+        if ( rc )
+            break;
+    }
+
+    return rc;
+}
+
+/* Internal struct to store the emulated PCI registers. */
+struct vpci_register {
+    vpci_read_t read;
+    vpci_write_t write;
+    unsigned int size;
+    unsigned int offset;
+    void *priv_data;
+    struct rb_node node;
+};
+
+static bool vpci_register_overlap(const struct vpci_register *r,
+                                  unsigned int offset)
+{
+    if ( offset >= r->offset && offset < r->offset + r->size )
+        return true;
+
+    return false;
+}
+
+
+static int vpci_register_cmp(const struct vpci_register *r1,
+                             const struct vpci_register *r2)
+{
+    /* Make sure there's no overlap between registers. */
+    if ( vpci_register_overlap(r1, r2->offset) ||
+         vpci_register_overlap(r1, r2->offset + r2->size - 1) ||
+         vpci_register_overlap(r2, r1->offset) ||
+         vpci_register_overlap(r2, r1->offset + r1->size - 1) )
+        return 0;
+
+    if (r1->offset < r2->offset)
+        return -1;
+    else if (r1->offset > r2->offset)
+        return 1;
+
+    ASSERT_UNREACHABLE();
+    return 0;
+}
+
+static struct vpci_register *vpci_find_register(const struct pci_dev *pdev,
+                                                unsigned int reg,
+                                                unsigned int size)
+{
+    struct rb_node *node;
+    struct vpci_register r = {
+        .offset = reg,
+        .size = size,
+    };
+
+    node = pdev->vpci->handlers.rb_node;
+    while ( node )
+    {
+        struct vpci_register *t =
+            container_of(node, struct vpci_register, node);
+
+        switch ( vpci_register_cmp(&r, t) )
+        {
+        case -1:
+            node = node->rb_left;
+            break;
+        case 1:
+            node = node->rb_right;
+            break;
+        default:
+            return t;
+        }
+    }
+
+    return NULL;
+}
+
+int xen_vpci_add_register(struct pci_dev *pdev, vpci_read_t read_handler,
+                          vpci_write_t write_handler, unsigned int offset,
+                          unsigned int size, void *data)
+{
+    struct rb_node **new, *parent;
+    struct vpci_register *r;
+
+    /*
+     * In order to avoid using locks to protect the RB tree that contains the
+     * handlers prevent adding them unless the domain is paused (and then
+     * calls to xen_vpci_add_register should also be serialized).
+     */
+    ASSERT(atomic_read(&pdev->domain->pause_count));
+
+    /* Some sanity checks. */
+    if ( (size != 1 && size != 2 && size != 4) || offset >= 0xFFF ||
+         offset & (size - 1) || read_handler == NULL || write_handler == NULL )
+        return -EINVAL;
+
+    r = xzalloc(struct vpci_register);
+    if ( !r )
+        return -ENOMEM;
+
+    r->read = read_handler;
+    r->write = write_handler;
+    r->size = size;
+    r->offset = offset;
+    r->priv_data = data;
+
+    new = &pdev->vpci->handlers.rb_node;
+    parent = NULL;
+
+    while (*new) {
+        struct vpci_register *this =
+            container_of(*new, struct vpci_register, node);
+
+        parent = *new;
+        switch ( vpci_register_cmp(r, this) )
+        {
+        case -1:
+            new = &((*new)->rb_left);
+            break;
+        case 1:
+            new = &((*new)->rb_right);
+            break;
+        default:
+            xfree(r);
+            return -EEXIST;
+        }
+    }
+
+    rb_link_node(&r->node, parent, new);
+    rb_insert_color(&r->node, &pdev->vpci->handlers);
+
+    return 0;
+}
+
+int xen_vpci_remove_register(struct pci_dev *pdev, unsigned int offset)
+{
+    struct vpci_register *r;
+
+    r = vpci_find_register(pdev, offset, 1 /* size doesn't matter here. */);
+    if ( !r )
+        return -ENOENT;
+
+    rb_erase(&r->node, &pdev->vpci->handlers);
+    xfree(r);
+
+    return 0;
+}
+
+/* Wrappers for performing reads/writes to the underlying hardware. */
+static void vpci_read_hw(unsigned int seg, unsigned int bus,
+                         unsigned int devfn, unsigned int reg, uint32_t size,
+                         uint32_t *data)
+{
+    switch ( size )
+    {
+    case 4:
+        *data = pci_conf_read32(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
+                                reg);
+        break;
+    case 3:
+        /*
+         * This is possible because a 4byte read can have 1byte trapped and
+         * the rest passed-through.
+         */
+        *data = pci_conf_read16(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
+                                reg + 1) << 8;
+        *data |= pci_conf_read8(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
+                               reg);
+        break;
+    case 2:
+        *data = pci_conf_read16(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
+                                reg);
+        break;
+    case 1:
+        *data = pci_conf_read8(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn),
+                               reg);
+        break;
+    default:
+        BUG();
+    }
+}
+
+static void vpci_write_hw(unsigned int seg, unsigned int bus,
+                          unsigned int devfn, unsigned int reg, uint32_t size,
+                          uint32_t data)
+{
+    switch ( size )
+    {
+    case 4:
+        pci_conf_write32(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn), reg,
+                         data);
+        break;
+    case 3:
+        /*
+         * This is possible because a 4byte write can have 1byte trapped and
+         * the rest passed-through.
+         */
+        pci_conf_write8(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn), reg, data);
+        pci_conf_write16(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn), reg + 1,
+                         data >> 8);
+        break;
+    case 2:
+        pci_conf_write16(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn), reg,
+                         data);
+        break;
+    case 1:
+        pci_conf_write8(seg, bus, PCI_SLOT(devfn), PCI_FUNC(devfn), reg, data);
+        break;
+    default:
+        BUG();
+    }
+}
+
+/* Helper macros for the read/write handlers. */
+#define GENMASK_BYTES(e, s) GENMASK((e) * 8, (s) * 8)
+#define SHIFT_RIGHT_BYTES(d, o) d >>= (o) * 8
+#define ADD_RESULT(r, d, s, o) r |= ((d) & GENMASK_BYTES(s, 0)) << ((o) * 8)
+
+int xen_vpci_read(unsigned int seg, unsigned int bus, unsigned int devfn,
+                  unsigned int reg, uint32_t size, uint32_t *data)
+{
+    struct domain *d = current->domain;
+    struct pci_dev *pdev;
+    const struct vpci_register *r;
+    union vpci_val val = { .double_word = 0 };
+    unsigned int data_rshift = 0, data_lshift = 0, data_size;
+    uint32_t tmp_data;
+    int rc;
+
+    *data = 0;
+
+    /* Find the PCI dev matching the address. */
+    pdev = pci_get_pdev_by_domain(d, seg, bus, devfn);
+    if ( !pdev )
+        goto passthrough;
+
+    /* Find the vPCI register handler. */
+    r = vpci_find_register(pdev, reg, size);
+    if ( !r )
+        goto passthrough;
+
+    if ( r->offset > reg )
+    {
+        /*
+         * There's a heading gap into the emulated register.
+         * NB: it's possible for this recursive call to have a size of 3.
+         */
+        rc = xen_vpci_read(seg, bus, devfn, reg, r->offset - reg, &tmp_data);
+        if ( rc )
+            return rc;
+
+        /* Add the head read to the partial result. */
+        ADD_RESULT(*data, tmp_data, r->offset - reg, 0);
+        data_lshift = r->offset - reg;
+
+        /* Account for the read. */
+        size -= data_lshift;
+        reg += data_lshift;
+    }
+    else if ( r->offset < reg )
+        /* There's an offset into the emulated register */
+        data_rshift = reg - r->offset;
+
+    ASSERT(data_lshift == 0 || data_rshift == 0);
+    data_size = min(size, r->size - data_rshift);
+    ASSERT(data_size != 0);
+
+    /* Perform the read of the register. */
+    rc = r->read(pdev, r->offset, &val, r->priv_data);
+    if ( rc )
+        return rc;
+
+    val.double_word >>= data_rshift * 8;
+    ADD_RESULT(*data, val.double_word, data_size, data_lshift);
+
+    /* Account for the read */
+    size -= data_size;
+    reg += data_size;
+
+    /* Read the remaining, if any. */
+    if ( size > 0 )
+    {
+        /*
+         * Read tailing data.
+         * NB: it's possible for this recursive call to have a size of 3.
+         */
+        rc = xen_vpci_read(seg, bus, devfn, reg, size, &tmp_data);
+        if ( rc )
+            return rc;
+
+        /* Add the tail read to the partial result. */
+        ADD_RESULT(*data, tmp_data, size, data_size + data_lshift);
+    }
+
+    return 0;
+
+ passthrough:
+    vpci_read_hw(seg, bus, devfn, reg, size, data);
+    return 0;
+}
+
+/* Perform a maybe partial write to a register. */
+static int vpci_write_helper(struct pci_dev *pdev,
+                             const struct vpci_register *r, unsigned int size,
+                             unsigned int offset, uint32_t data)
+{
+    union vpci_val val = { .double_word = data };
+    int rc;
+
+    ASSERT(size <= r->size);
+    if ( size != r->size )
+    {
+        rc = r->read(pdev, r->offset, &val, r->priv_data);
+        if ( rc )
+            return rc;
+        val.double_word &= ~GENMASK_BYTES(size + offset, offset);
+        data &= GENMASK_BYTES(size, 0);
+        val.double_word |= data << (offset * 8);
+    }
+
+    return r->write(pdev, r->offset, val, r->priv_data);
+}
+
+int xen_vpci_write(unsigned int seg, unsigned int bus, unsigned int devfn,
+                   unsigned int reg, uint32_t size, uint32_t data)
+{
+    struct domain *d = current->domain;
+    struct pci_dev *pdev;
+    struct vpci_register *r;
+    unsigned int data_size, data_offset = 0;
+    int rc;
+
+    /* Find the PCI dev matching the address. */
+    pdev = pci_get_pdev_by_domain(d, seg, bus, devfn);
+    if ( !pdev )
+        goto passthrough;
+
+    /* Find the vPCI register handler. */
+    r = vpci_find_register(pdev, reg, size);
+    if ( !r )
+        goto passthrough;
+
+    else if ( r->offset > reg )
+    {
+        /*
+         * There's a heading gap into the emulated register found.
+         * NB: it's possible for this recursive call to have a size of 3.
+         */
+        rc = xen_vpci_write(seg, bus, devfn, reg, r->offset - reg, data);
+        if ( rc )
+            return rc;
+
+        /* Advance the data by the written size. */
+        SHIFT_RIGHT_BYTES(data, r->offset - reg);
+        size -= r->offset - reg;
+        reg += r->offset - reg;
+    }
+    else if ( r->offset < reg )
+        /* There's an offset into the emulated register. */
+        data_offset = reg - r->offset;
+
+    data_size = min(size, r->size - data_offset);
+
+    /* Perform the write of the register. */
+    ASSERT(data_size != 0);
+    rc = vpci_write_helper(pdev, r, data_size, data_offset, data);
+    if ( rc )
+        return rc;
+
+    /* Account for the read */
+    size -= data_size;
+    reg += data_size;
+    SHIFT_RIGHT_BYTES(data, data_size);
+
+    /* Write the remaining, if any. */
+    if ( size > 0 )
+    {
+        /*
+         * Write tailing data.
+         * NB: it's possible for this recursive call to have a size of 3.
+         */
+        rc = xen_vpci_write(seg, bus, devfn, reg, size, data);
+        if ( rc )
+            return rc;
+    }
+
+    return 0;
+
+ passthrough:
+    vpci_write_hw(seg, bus, devfn, reg, size, data);
+    return 0;
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
+
diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index 6ab987f231..f0741917ed 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -426,6 +426,7 @@ struct arch_domain
 #define has_vpit(d)        (!!((d)->arch.emulation_flags & XEN_X86_EMU_PIT))
 #define has_pirq(d)        (!!((d)->arch.emulation_flags & \
                             XEN_X86_EMU_USE_PIRQ))
+#define has_vpci(d)        (!!((d)->arch.emulation_flags & XEN_X86_EMU_VPCI))
 
 #define has_arch_pdevs(d)    (!list_empty(&(d)->arch.pdev_list))
 
diff --git a/xen/include/asm-x86/hvm/io.h b/xen/include/asm-x86/hvm/io.h
index 2484eb1c75..2dbf92f13e 100644
--- a/xen/include/asm-x86/hvm/io.h
+++ b/xen/include/asm-x86/hvm/io.h
@@ -155,6 +155,9 @@ extern void hvm_dpci_msi_eoi(struct domain *d, int vector);
  */
 void register_g2m_portio_handler(struct domain *d);
 
+/* HVM port IO handler for PCI accesses. */
+void register_vpci_portio_handler(struct domain *d);
+
 #endif /* __ASM_X86_HVM_IO_H__ */
 
 
diff --git a/xen/include/public/arch-x86/xen.h 
b/xen/include/public/arch-x86/xen.h
index 8a9ba7982b..c00f8cda93 100644
--- a/xen/include/public/arch-x86/xen.h
+++ b/xen/include/public/arch-x86/xen.h
@@ -295,12 +295,15 @@ struct xen_arch_domainconfig {
 #define XEN_X86_EMU_PIT             (1U<<_XEN_X86_EMU_PIT)
 #define _XEN_X86_EMU_USE_PIRQ       9
 #define XEN_X86_EMU_USE_PIRQ        (1U<<_XEN_X86_EMU_USE_PIRQ)
+#define _XEN_X86_EMU_VPCI           10
+#define XEN_X86_EMU_VPCI            (1U<<_XEN_X86_EMU_VPCI)
 
 #define XEN_X86_EMU_ALL             (XEN_X86_EMU_LAPIC | XEN_X86_EMU_HPET |  \
                                      XEN_X86_EMU_PM | XEN_X86_EMU_RTC |      \
                                      XEN_X86_EMU_IOAPIC | XEN_X86_EMU_PIC |  \
                                      XEN_X86_EMU_VGA | XEN_X86_EMU_IOMMU |   \
-                                     XEN_X86_EMU_PIT | XEN_X86_EMU_USE_PIRQ)
+                                     XEN_X86_EMU_PIT | XEN_X86_EMU_USE_PIRQ |\
+                                     XEN_X86_EMU_VPCI)
     uint32_t emulation_flags;
 };
 
diff --git a/xen/include/xen/pci.h b/xen/include/xen/pci.h
index 74d828db38..3d3853fd6f 100644
--- a/xen/include/xen/pci.h
+++ b/xen/include/xen/pci.h
@@ -13,6 +13,7 @@
 #include <xen/irq.h>
 #include <xen/pci_regs.h>
 #include <xen/pfn.h>
+#include <xen/rbtree.h>
 #include <asm/device.h>
 #include <asm/numa.h>
 #include <asm/pci.h>
@@ -88,6 +89,9 @@ struct pci_dev {
 #define PT_FAULT_THRESHOLD 10
     } fault;
     u64 vf_rlen[6];
+
+    /* Data for vPCI. */
+    struct vpci *vpci;
 };
 
 #define for_each_pdev(domain, pdev) \
diff --git a/xen/include/xen/vpci.h b/xen/include/xen/vpci.h
new file mode 100644
index 0000000000..2f54919310
--- /dev/null
+++ b/xen/include/xen/vpci.h
@@ -0,0 +1,62 @@
+#ifndef _VPCI_
+#define _VPCI_
+
+#include <xen/pci.h>
+#include <xen/types.h>
+
+/*
+ * Guest handlers for PCI register accesses.
+ *
+ * sval: internal stored value (usage up to the handler).
+ * {r/w}val: read/write value from the guest.
+ */
+
+union vpci_val {
+    uint8_t half_word;
+    uint16_t word;
+    uint32_t double_word;
+};
+
+typedef int (*vpci_read_t)(struct pci_dev *pdev, unsigned int reg,
+                           union vpci_val *val, void *data);
+
+typedef int (*vpci_write_t)(struct pci_dev *pdev, unsigned int reg,
+                            union vpci_val val, void *data);
+
+typedef int (*vpci_register_init_t)(struct pci_dev *dev);
+
+#define REGISTER_VPCI_INIT(x) \
+  static const vpci_register_init_t x##_entry __used_section(".data.vpci") = x
+
+/* Add vPCI handlers to device. */
+int xen_vpci_add_handlers(struct pci_dev *dev);
+
+/* Add/remove a register handler. */
+int xen_vpci_add_register(struct pci_dev *pdev, vpci_read_t read_handler,
+                          vpci_write_t write_handler, unsigned int offset,
+                          unsigned int size, void *data);
+int xen_vpci_remove_register(struct pci_dev *pdev, unsigned int offset);
+
+/* Generic read/write handlers for the PCI config space. */
+int xen_vpci_read(unsigned int seg, unsigned int bus, unsigned int devfn,
+                  unsigned int reg, uint32_t size, uint32_t *data);
+int xen_vpci_write(unsigned int seg, unsigned int bus, unsigned int devfn,
+                   unsigned int reg, uint32_t size, uint32_t data);
+
+struct vpci {
+    /* Root pointer for the tree of vPCI handlers. */
+    struct rb_root handlers;
+};
+
+#endif
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
+
-- 
2.11.0 (Apple Git-81)


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