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[Xen-devel] [PATCH v9 07/11] vpci/bars: add handlers to map the BARs



Introduce a set of handlers that trap accesses to the PCI BARs and the
command register, in order to snoop BAR sizing and BAR relocation.

The command handler is used to detect changes to bit 2 (response to
memory space accesses), and maps/unmaps the BARs of the device into
the guest p2m. A rangeset is used in order to figure out which memory
to map/unmap. This makes it easier to keep track of the possible
overlaps with other BARs, and will also simplify MSI-X support, where
certain regions of a BAR might be used for the MSI-X table or PBA.

The BAR register handlers are used to detect attempts by the guest to
size or relocate the BARs.

Note that the long running BAR mapping and unmapping operations are
deferred to be performed by hvm_io_pending, so that they can be safely
preempted.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: George Dunlap <George.Dunlap@xxxxxxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Tim Deegan <tim@xxxxxxx>
Cc: Paul Durrant <paul.durrant@xxxxxxxxxx>
---
Changes since v8:
 - Do not pretend to support ARM in the map_range function. Explain
   the required changes in the comment.
 - Introduce PCI_HEADER_{NORMAL/BRIDGE}_NR_BARS defines.
 - Rename 'rom' boolean variable to 'rom_only', which is more
   descriptive of it's meaning.
 - Introduce vpci_remove_device which removes all handlers for a
   device.
 - Simplify error handling when modifying BARs mapping. Any error will
   cause the device to be unplugged (by calling vpci_remove_device).
 - Return an error code in modify_bars. Add comments describing why
   the error is sometimes ignored.

Changes since v7:
 - Order includes.
 - Add newline between switch cases.
 - Fix typo in comment (hopping).
 - Wrap ternary conditional in parentheses.
 - Remove CONFIG_HAS_PCI gueard from sched.h vpci_vcpu usage.
 - Add comment regarding vpci_vcpu usage.
 - Move rom_enabled from BAR struct to header.
 - Do not protect vpci_vcpu with __XEN__ guards.

Changes since v6:
 - s/vpci_check_pending/vpci_process_pending/.
 - Improve error handling in vpci_process_pending.
 - Add a comment that explains how vpci_check_bar_overlap works.
 - Add error messages to vpci_modify_bars and vpci_modify_rom.
 - Introduce vpci_hw_read16/32, in order to passthrough reads to
   the underlying hw.
 - Print BAR number on error in vpci_bar_write.
 - Place the CONFIG_HAS_PCI guards inside the vpci.h header and
   provide an empty vpci_vcpu structure for the !CONFIG_HAS_PCI case.
 - Define CONFIG_HAS_PCI in the test harness emul.h header before
   including vpci.h
 - Add ARM TODOs and an ARM-specific bodge to vpci_map_range due to
   the lack of preemption in {un}map_mmio_regions.
 - Make vpci_maybe_defer_map void.
 - Set rom_enabled in vpci_init_bars.
 - Defer enabling/disabling the memory decoding (or the ROM enable
   bit) until the memory has been mapped/unmapped.
 - Remove vpci_ prefix from static functions.
 - Use the same code in order to map the general BARs and the ROM
   BARs.
 - Remove the seg/bus local variables and use pdev->{seg,bus} instead.
 - Convert the bools in the BAR related structs into bool bitfields.
 - Add the must_check attribute to vpci_process_pending.
 - Open code check_bar_overlap inside modify_bars, which was it's only
   user.

Changes since v5:
 - Switch to the new handler type.
 - Use pci_sbdf_t to size the BARs.
 - Use a single return for vpci_modify_bar.
 - Do not return an error code from vpci_modify_bars, just log the
   failure.
 - Remove the 'sizing' parameter. Instead just let the guest write
   directly to the BAR, and read the value back. This simplifies the
   BAR register handlers, specially the read one.
 - Ignore ROM BAR writes with memory decoding enabled and ROM enabled.
 - Do not propagate failures to setup the ROM BAR in vpci_init_bars.
 - Add preemption support to the BAR mapping/unmapping operations.

Changes since v4:
 - Expand commit message to mention the reason behind the usage of
   rangesets.
 - Fix comment related to the inclusiveness of rangesets.
 - Fix off-by-one error in the calculation of the end of memory
   regions.
 - Store the state of the BAR (mapped/unmapped) in the vpci_bar
   enabled field, previously was only used by ROMs.
 - Fix double negation of return code.
 - Modify vpci_cmd_write so it has a single call to pci_conf_write16.
 - Print a warning when trying to write to the BAR with memory
   decoding enabled (and ignore the write).
 - Remove header_type local variable, it's used only once.
 - Move the read of the command register.
 - Restore previous command register value in the exit paths.
 - Only set address to INVALID_PADDR if the initial BAR value matches
    ~0 & PCI_BASE_ADDRESS_MEM_MASK.
 - Don't disable the enabled bit in the expansion ROM register, memory
   decoding is already disabled and takes precedence.
 - Don't use INVALID_PADDR, just set the initial BAR address to the
   value found in the hardware.
 - Introduce rom_enabled to store the status of the
   PCI_ROM_ADDRESS_ENABLE bit.
 - Reorder fields of the structure to prevent holes.

Changes since v3:
 - Propagate previous changes: drop xen_ prefix and use u8/u16/u32
   instead of the previous half_word/word/double_word.
 - Constify some of the paramerters.
 - s/VPCI_BAR_MEM/VPCI_BAR_MEM32/.
 - Simplify the number of fields stored for each BAR, a single address
   field is stored and contains the address of the BAR both on Xen and
   in the guest.
 - Allow the guest to move the BARs around in the physical memory map.
 - Add support for expansion ROM BARs.
 - Do not cache the value of the command register.
 - Remove a label used in vpci_cmd_write.
 - Fix the calculation of the sizing mask in vpci_bar_write.
 - Check the memory decode bit in order to decide if a BAR is
   positioned or not.
 - Disable memory decoding before sizing the BARs in Xen.
 - When mapping/unmapping BARs check if there's overlap between BARs,
   in order to avoid unmapping memory required by another BAR.
 - Introduce a macro to check whether a BAR is mappable or not.
 - Add a comment regarding the lack of support for SR-IOV.
 - Remove the usage of the GENMASK macro.

Changes since v2:
 - Detect unset BARs and allow the hardware domain to position them.
---
 tools/tests/vpci/emul.h   |   1 +
 xen/arch/x86/hvm/ioreq.c  |   4 +
 xen/drivers/vpci/Makefile |   2 +-
 xen/drivers/vpci/header.c | 545 ++++++++++++++++++++++++++++++++++++++++++++++
 xen/drivers/vpci/vpci.c   |  45 ++--
 xen/include/xen/sched.h   |   4 +
 xen/include/xen/vpci.h    |  62 ++++++
 7 files changed, 649 insertions(+), 14 deletions(-)
 create mode 100644 xen/drivers/vpci/header.c

diff --git a/tools/tests/vpci/emul.h b/tools/tests/vpci/emul.h
index fd0317995a..5d47544bf7 100644
--- a/tools/tests/vpci/emul.h
+++ b/tools/tests/vpci/emul.h
@@ -80,6 +80,7 @@ typedef union {
     };
 } pci_sbdf_t;
 
+#define CONFIG_HAS_VPCI
 #include "vpci.h"
 
 #define __hwdom_init
diff --git a/xen/arch/x86/hvm/ioreq.c b/xen/arch/x86/hvm/ioreq.c
index 7e66965bcd..90c9e3cd59 100644
--- a/xen/arch/x86/hvm/ioreq.c
+++ b/xen/arch/x86/hvm/ioreq.c
@@ -26,6 +26,7 @@
 #include <xen/domain.h>
 #include <xen/event.h>
 #include <xen/paging.h>
+#include <xen/vpci.h>
 
 #include <asm/hvm/hvm.h>
 #include <asm/hvm/ioreq.h>
@@ -48,6 +49,9 @@ bool hvm_io_pending(struct vcpu *v)
     struct domain *d = v->domain;
     struct hvm_ioreq_server *s;
 
+    if ( has_vpci(d) && vpci_process_pending(v) )
+        return true;
+
     list_for_each_entry ( s,
                           &d->arch.hvm_domain.ioreq_server.list,
                           list_entry )
diff --git a/xen/drivers/vpci/Makefile b/xen/drivers/vpci/Makefile
index 840a906470..241467212f 100644
--- a/xen/drivers/vpci/Makefile
+++ b/xen/drivers/vpci/Makefile
@@ -1 +1 @@
-obj-y += vpci.o
+obj-y += vpci.o header.o
diff --git a/xen/drivers/vpci/header.c b/xen/drivers/vpci/header.c
new file mode 100644
index 0000000000..8d697b670b
--- /dev/null
+++ b/xen/drivers/vpci/header.c
@@ -0,0 +1,545 @@
+/*
+ * Generic functionality for handling accesses to the PCI header from the
+ * configuration space.
+ *
+ * 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/p2m-common.h>
+#include <xen/sched.h>
+#include <xen/softirq.h>
+#include <xen/vpci.h>
+
+#include <asm/event.h>
+
+#define MAPPABLE_BAR(x)                                                 \
+    ((x)->type == VPCI_BAR_MEM32 || (x)->type == VPCI_BAR_MEM64_LO ||   \
+     (x)->type == VPCI_BAR_ROM)
+
+struct map_data {
+    struct domain *d;
+    bool map;
+};
+
+static int map_range(unsigned long s, unsigned long e, void *data,
+                     unsigned long *c)
+{
+    const struct map_data *map = data;
+    int rc;
+
+    for ( ; ; )
+    {
+        unsigned long size = e - s + 1;
+
+        /*
+         * ARM TODOs:
+         * - On ARM whether the memory is prefetchable or not should be passed
+         *   to map_mmio_regions in order to decide which memory attributes
+         *   should be used.
+         *
+         * - {un}map_mmio_regions doesn't support preemption.
+         */
+
+        rc = (map->map ? map_mmio_regions : unmap_mmio_regions)
+             (map->d, _gfn(s), size, _mfn(s));
+        if ( rc == 0 )
+        {
+            *c += size;
+            break;
+        }
+        if ( rc < 0 )
+        {
+            printk(XENLOG_G_WARNING
+                   "Failed to identity %smap [%" PRI_gfn ", %" PRI_gfn "] for 
d%d: %d\n",
+                   map ? "" : "un", s, e, map->d->domain_id, rc);
+            break;
+        }
+        ASSERT(rc < size);
+        *c += rc;
+        s += rc;
+        if ( general_preempt_check() )
+        {
+            if ( !is_idle_vcpu(current) )
+                return -ERESTART;
+
+            process_pending_softirqs();
+        }
+    }
+
+    return rc;
+}
+
+static void modify_decoding(const struct pci_dev *pdev, bool map, bool 
rom_only)
+{
+    struct vpci_header *header = &pdev->vpci->header;
+    uint8_t slot = PCI_SLOT(pdev->devfn), func = PCI_FUNC(pdev->devfn);
+    unsigned int i;
+
+    for ( i = 0; i < ARRAY_SIZE(header->bars); i++ )
+    {
+        if ( rom_only && header->bars[i].type == VPCI_BAR_ROM )
+        {
+            unsigned int rom_pos = (i == PCI_HEADER_NORMAL_NR_BARS)
+                                   ? PCI_ROM_ADDRESS : PCI_ROM_ADDRESS1;
+            uint32_t val = pci_conf_read32(pdev->seg, pdev->bus, slot, func,
+                                           rom_pos);
+
+            header->bars[i].enabled = header->rom_enabled = map;
+
+            val &= ~PCI_ROM_ADDRESS_ENABLE;
+            val |= map ? PCI_ROM_ADDRESS_ENABLE : 0;
+            pci_conf_write32(pdev->seg, pdev->bus, slot, func, rom_pos, val);
+            break;
+        }
+        if ( !rom_only && (header->bars[i].type != VPCI_BAR_ROM ||
+                           header->rom_enabled) )
+            header->bars[i].enabled = map;
+    }
+
+    if ( !rom_only )
+    {
+        uint16_t cmd = pci_conf_read16(pdev->seg, pdev->bus, slot,
+                                       func, PCI_COMMAND);
+
+        cmd &= ~PCI_COMMAND_MEMORY;
+        cmd |= map ? PCI_COMMAND_MEMORY : 0;
+        pci_conf_write16(pdev->seg, pdev->bus, slot, func, PCI_COMMAND,
+                         cmd);
+    }
+}
+
+bool vpci_process_pending(struct vcpu *v)
+{
+    if ( v->vpci.mem )
+    {
+        struct map_data data = {
+            .d = v->domain,
+            .map = v->vpci.map,
+        };
+        int rc = rangeset_consume_ranges(v->vpci.mem, map_range, &data);
+
+        if ( rc == -ERESTART )
+            return true;
+
+        spin_lock(&v->vpci.pdev->vpci->lock);
+        /* Disable memory decoding unconditionally on failure. */
+        modify_decoding(v->vpci.pdev, rc ? false : v->vpci.map,
+                        rc ? false : v->vpci.rom);
+        spin_unlock(&v->vpci.pdev->vpci->lock);
+
+        rangeset_destroy(v->vpci.mem);
+        v->vpci.mem = NULL;
+        if ( rc )
+            /*
+             * FIXME: in case of failure remove the device from the domain.
+             * Note that there might still be leftover mappings. While this is
+             * safe for Dom0, for DomUs the domain will likely need to be
+             * killed in order to avoid leaking stale p2m mappings on
+             * failure.
+             */
+            vpci_remove_device(v->vpci.pdev);
+    }
+
+    return false;
+}
+
+static int maybe_defer_map(struct domain *d, struct pci_dev *pdev,
+                           struct rangeset *mem, bool map, bool rom)
+{
+    struct vcpu *curr = current;
+    int rc;
+
+    if ( is_idle_vcpu(curr) )
+    {
+        struct map_data data = { .d = d, .map = true };
+
+        /*
+         * Dom0 building runs on the idle vCPU, in which case it's not possible
+         * to defer the operation (like done in the else branch). Call
+         * rangeset_consume_ranges in order to establish the mappings right
+         * away.
+         */
+        ASSERT(map && !rom);
+        rc = rangeset_consume_ranges(mem, map_range, &data);
+        rangeset_destroy(mem);
+        if ( rc )
+            return rc;
+        modify_decoding(pdev, true, false);
+    }
+    else
+    {
+        /*
+         * FIXME: when deferring the {un}map the state of the device should not
+         * be trusted. For example the enable bit is toggled after the device
+         * is mapped. This can lead to parallel mapping operations being
+         * started for the same device if the domain is not well-behaved.
+         */
+        ASSERT(curr->domain == d);
+        curr->vpci.pdev = pdev;
+        curr->vpci.mem = mem;
+        curr->vpci.map = map;
+        curr->vpci.rom = rom;
+    }
+
+    return 0;
+}
+
+static int modify_bars(const struct pci_dev *pdev, bool map, bool rom_only)
+{
+    struct vpci_header *header = &pdev->vpci->header;
+    struct rangeset *mem = rangeset_new(NULL, NULL, 0);
+    struct pci_dev *tmp, *dev = NULL;
+    unsigned int i;
+    int rc;
+
+    if ( !mem )
+        return -ENOMEM;
+
+    /*
+     * Create a rangeset that represents the current device BARs memory region
+     * and compare it against all the currently active BAR memory regions. If
+     * an overlap is found, subtract it from the region to be
+     * mapped/unmapped.
+     *
+     * NB: the rangeset uses inclusive frame numbers.
+     */
+
+    /*
+     * First fill the rangeset with all the BARs of this device or with the ROM
+     * BAR only, depending on whether the guest is toggling the memory decode
+     * bit of the command register, or the enable bit of the ROM BAR register.
+     */
+    for ( i = 0; i < ARRAY_SIZE(header->bars); i++ )
+    {
+        const struct vpci_bar *bar = &header->bars[i];
+
+        if ( !MAPPABLE_BAR(bar) ||
+             (rom_only ? bar->type != VPCI_BAR_ROM
+                       : (bar->type == VPCI_BAR_ROM && !header->rom_enabled)) )
+            continue;
+
+        rc = rangeset_add_range(mem, PFN_DOWN(bar->addr),
+                                PFN_UP(bar->addr + bar->size - 1));
+        if ( rc )
+        {
+            printk(XENLOG_G_WARNING
+                   "Failed to add [%" PRI_gfn ", %" PRI_gfn "]: %d\n",
+                   PFN_DOWN(bar->addr), PFN_UP(bar->addr + bar->size - 1),
+                   rc);
+            rangeset_destroy(mem);
+            return rc;
+        }
+    }
+
+    /*
+     * Check for overlaps with other BARs. Note that only BARs that are
+     * currently mapped (enabled) are checked for overlaps.
+     */
+    list_for_each_entry(tmp, &pdev->domain->arch.pdev_list, domain_list)
+    {
+        if ( tmp == pdev )
+        {
+            /*
+             * Need to store the device so it's not constified and
+             * maybe_defer_map can modify it in case of error.
+             */
+            dev = tmp;
+            if ( !rom_only )
+                /*
+                 * If memory decoding is toggled avoid checking against the
+                 * same device, or else all regions will be removed from the
+                 * memory map in the unmap case.
+                 */
+                continue;
+        }
+
+        for ( i = 0; i < ARRAY_SIZE(tmp->vpci->header.bars); i++ )
+        {
+            const struct vpci_bar *bar = &tmp->vpci->header.bars[i];
+            unsigned long start = PFN_DOWN(bar->addr);
+            unsigned long end = PFN_UP(bar->addr + bar->size - 1);
+
+            if ( !bar->enabled || !rangeset_overlaps_range(mem, start, end) ||
+                 /*
+                  * If only the ROM bit is toggled check against other BARs in
+                  * the same device for overlaps, but not against the ROM BAR.
+                  */
+                 (rom_only && tmp == pdev && bar->type == VPCI_BAR_ROM) )
+                continue;
+
+            rc = rangeset_remove_range(mem, start, end);
+            if ( rc )
+            {
+                printk(XENLOG_G_WARNING
+                       "Failed to remove [%" PRI_gfn ", %" PRI_gfn "]: %d\n",
+                       start, end, rc);
+                rangeset_destroy(mem);
+                return rc;
+            }
+        }
+    }
+
+    ASSERT(dev);
+
+    return maybe_defer_map(pdev->domain, dev, mem, map, rom_only);
+}
+
+static void cmd_write(const struct pci_dev *pdev, unsigned int reg,
+                      uint32_t cmd, void *data)
+{
+    uint8_t slot = PCI_SLOT(pdev->devfn), func = PCI_FUNC(pdev->devfn);
+    uint16_t current_cmd = pci_conf_read16(pdev->seg, pdev->bus, slot, func,
+                                           reg);
+
+    /*
+     * Let Dom0 play with all the bits directly except for the memory
+     * decoding one.
+     */
+    if ( (cmd ^ current_cmd) & PCI_COMMAND_MEMORY )
+        /*
+         * Ignore the error. No memory has been added or removed from the p2m,
+         * and the memory decoding has not been changed, so leave everything
+         * as-is, hoping the guest will realize and try again.
+         */
+        modify_bars(pdev, cmd & PCI_COMMAND_MEMORY, false);
+    else
+        pci_conf_write16(pdev->seg, pdev->bus, slot, func, reg, cmd);
+}
+
+static void bar_write(const struct pci_dev *pdev, unsigned int reg,
+                      uint32_t val, void *data)
+{
+    struct vpci_bar *bar = data;
+    uint8_t slot = PCI_SLOT(pdev->devfn), func = PCI_FUNC(pdev->devfn);
+    bool hi = false;
+
+    if ( pci_conf_read16(pdev->seg, pdev->bus, slot, func, PCI_COMMAND) &
+         PCI_COMMAND_MEMORY )
+    {
+        gprintk(XENLOG_WARNING,
+                "%04x:%02x:%02x.%u: ignored BAR %lu write with memory decoding 
enabled\n",
+                pdev->seg, pdev->bus, slot, func,
+                bar - pdev->vpci->header.bars);
+        return;
+    }
+
+    if ( bar->type == VPCI_BAR_MEM64_HI )
+    {
+        ASSERT(reg > PCI_BASE_ADDRESS_0);
+        bar--;
+        hi = true;
+    }
+    else
+        val &= PCI_BASE_ADDRESS_MEM_MASK;
+
+    /*
+     * Update the cached address, so that when memory decoding is enabled
+     * Xen can map the BAR into the guest p2m.
+     */
+    bar->addr &= ~(0xffffffffull << (hi ? 32 : 0));
+    bar->addr |= (uint64_t)val << (hi ? 32 : 0);
+
+    /* Make sure Xen writes back the same value for the BAR RO bits. */
+    if ( !hi )
+    {
+        val |= bar->type == VPCI_BAR_MEM32 ? PCI_BASE_ADDRESS_MEM_TYPE_32
+                                           : PCI_BASE_ADDRESS_MEM_TYPE_64;
+        val |= bar->prefetchable ? PCI_BASE_ADDRESS_MEM_PREFETCH : 0;
+    }
+
+    pci_conf_write32(pdev->seg, pdev->bus, PCI_SLOT(pdev->devfn),
+                     PCI_FUNC(pdev->devfn), reg, val);
+}
+
+static void rom_write(const struct pci_dev *pdev, unsigned int reg,
+                      uint32_t val, void *data)
+{
+    struct vpci_header *header = &pdev->vpci->header;
+    struct vpci_bar *rom = data;
+    uint8_t slot = PCI_SLOT(pdev->devfn), func = PCI_FUNC(pdev->devfn);
+    uint16_t cmd = pci_conf_read16(pdev->seg, pdev->bus, slot, func,
+                                   PCI_COMMAND);
+    bool new_enabled = val & PCI_ROM_ADDRESS_ENABLE;
+
+    if ( (cmd & PCI_COMMAND_MEMORY) && header->rom_enabled && new_enabled )
+    {
+        gprintk(XENLOG_WARNING,
+                "%04x:%02x:%02x.%u: ignored ROM BAR write with memory decoding 
enabled\n",
+                pdev->seg, pdev->bus, slot, func);
+        return;
+    }
+
+    if ( !header->rom_enabled )
+        rom->addr = val & PCI_ROM_ADDRESS_MASK;
+
+    /* Check if ROM BAR should be mapped/unmapped. */
+    if ( (cmd & PCI_COMMAND_MEMORY) && header->rom_enabled != new_enabled )
+    {
+        /*
+         * Return on error in order to avoid updating the 'addr' field. No
+         * memory has been added or removed from the p2m, and the memory
+         * decoding has not been changed, so leave everything as-is, hoping the
+         * guest will realize and try again.
+         */
+        if ( modify_bars(pdev, new_enabled, true) )
+            return;
+    }
+    else
+    {
+        header->rom_enabled = new_enabled;
+        pci_conf_write32(pdev->seg, pdev->bus, slot, func, reg, val);
+    }
+
+    if ( !new_enabled )
+        rom->addr = val & PCI_ROM_ADDRESS_MASK;
+}
+
+static int init_bars(struct pci_dev *pdev)
+{
+    uint8_t slot = PCI_SLOT(pdev->devfn), func = PCI_FUNC(pdev->devfn);
+    uint16_t cmd;
+    uint64_t addr, size;
+    unsigned int i, num_bars, rom_reg;
+    struct vpci_header *header = &pdev->vpci->header;
+    struct vpci_bar *bars = header->bars;
+    pci_sbdf_t sbdf = {
+        .seg = pdev->seg,
+        .bus = pdev->bus,
+        .dev = slot,
+        .func = func,
+    };
+    int rc;
+
+    switch ( pci_conf_read8(pdev->seg, pdev->bus, slot, func, PCI_HEADER_TYPE)
+             & 0x7f )
+    {
+    case PCI_HEADER_TYPE_NORMAL:
+        num_bars = PCI_HEADER_NORMAL_NR_BARS;
+        rom_reg = PCI_ROM_ADDRESS;
+        break;
+
+    case PCI_HEADER_TYPE_BRIDGE:
+        num_bars = PCI_HEADER_BRIDGE_NR_BARS;
+        rom_reg = PCI_ROM_ADDRESS1;
+        break;
+
+    default:
+        return -EOPNOTSUPP;
+    }
+
+    /* Setup a handler for the command register. */
+    rc = vpci_add_register(pdev->vpci, vpci_hw_read16, cmd_write, PCI_COMMAND,
+                           2, header);
+    if ( rc )
+        return rc;
+
+    /* Disable memory decoding before sizing. */
+    cmd = pci_conf_read16(pdev->seg, pdev->bus, slot, func, PCI_COMMAND);
+    if ( cmd & PCI_COMMAND_MEMORY )
+        pci_conf_write16(pdev->seg, pdev->bus, slot, func, PCI_COMMAND,
+                         cmd & ~PCI_COMMAND_MEMORY);
+
+    for ( i = 0; i < num_bars; i++ )
+    {
+        uint8_t reg = PCI_BASE_ADDRESS_0 + i * 4;
+        uint32_t val;
+
+        if ( i && bars[i - 1].type == VPCI_BAR_MEM64_LO )
+        {
+            bars[i].type = VPCI_BAR_MEM64_HI;
+            rc = vpci_add_register(pdev->vpci, vpci_hw_read32, bar_write, reg,
+                                   4, &bars[i]);
+            if ( rc )
+            {
+                pci_conf_write16(pdev->seg, pdev->bus, slot, func,
+                                 PCI_COMMAND, cmd);
+                return rc;
+            }
+
+            continue;
+        }
+
+        val = pci_conf_read32(pdev->seg, pdev->bus, slot, func, reg);
+        if ( (val & PCI_BASE_ADDRESS_SPACE) == PCI_BASE_ADDRESS_SPACE_IO )
+        {
+            bars[i].type = VPCI_BAR_IO;
+            continue;
+        }
+        if ( (val & PCI_BASE_ADDRESS_MEM_TYPE_MASK) ==
+             PCI_BASE_ADDRESS_MEM_TYPE_64 )
+            bars[i].type = VPCI_BAR_MEM64_LO;
+        else
+            bars[i].type = VPCI_BAR_MEM32;
+
+        rc = pci_size_mem_bar(sbdf, reg, &addr, &size,
+                              (i == num_bars - 1) ? PCI_BAR_LAST : 0);
+        if ( rc < 0 )
+        {
+            pci_conf_write16(pdev->seg, pdev->bus, slot, func, PCI_COMMAND,
+                             cmd);
+            return rc;
+        }
+
+        if ( size == 0 )
+        {
+            bars[i].type = VPCI_BAR_EMPTY;
+            continue;
+        }
+
+        bars[i].addr = addr;
+        bars[i].size = size;
+        bars[i].prefetchable = val & PCI_BASE_ADDRESS_MEM_PREFETCH;
+
+        rc = vpci_add_register(pdev->vpci, vpci_hw_read32, bar_write, reg, 4,
+                               &bars[i]);
+        if ( rc )
+        {
+            pci_conf_write16(pdev->seg, pdev->bus, slot, func, PCI_COMMAND,
+                             cmd);
+            return rc;
+        }
+    }
+
+    /* Check expansion ROM. */
+    rc = pci_size_mem_bar(sbdf, rom_reg, &addr, &size, PCI_BAR_ROM);
+    if ( rc > 0 && size )
+    {
+        struct vpci_bar *rom = &header->bars[num_bars];
+
+        rom->type = VPCI_BAR_ROM;
+        rom->size = size;
+        rom->addr = addr;
+        header->rom_enabled = pci_conf_read32(pdev->seg, pdev->bus, slot, func,
+                                              rom_reg) & 
PCI_ROM_ADDRESS_ENABLE;
+
+        rc = vpci_add_register(pdev->vpci, vpci_hw_read32, rom_write, rom_reg,
+                               4, rom);
+        if ( rc )
+            rom->type = VPCI_BAR_EMPTY;
+    }
+
+    return (cmd & PCI_COMMAND_MEMORY) ? modify_bars(pdev, true, false) : 0;
+}
+REGISTER_VPCI_INIT(init_bars);
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/drivers/vpci/vpci.c b/xen/drivers/vpci/vpci.c
index 4740d02edf..e5b49b9d82 100644
--- a/xen/drivers/vpci/vpci.c
+++ b/xen/drivers/vpci/vpci.c
@@ -34,6 +34,23 @@ struct vpci_register {
     struct list_head node;
 };
 
+void vpci_remove_device(struct pci_dev *pdev)
+{
+    spin_lock(&pdev->vpci->lock);
+    while ( !list_empty(&pdev->vpci->handlers) )
+    {
+        struct vpci_register *r = list_first_entry(&pdev->vpci->handlers,
+                                                   struct vpci_register,
+                                                   node);
+
+        list_del(&r->node);
+        xfree(r);
+    }
+    spin_unlock(&pdev->vpci->lock);
+    xfree(pdev->vpci);
+    pdev->vpci = NULL;
+}
+
 int __hwdom_init vpci_add_handlers(struct pci_dev *pdev)
 {
     unsigned int i;
@@ -57,19 +74,7 @@ int __hwdom_init vpci_add_handlers(struct pci_dev *pdev)
     }
 
     if ( rc )
-    {
-        while ( !list_empty(&pdev->vpci->handlers) )
-        {
-            struct vpci_register *r = list_first_entry(&pdev->vpci->handlers,
-                                                       struct vpci_register,
-                                                       node);
-
-            list_del(&r->node);
-            xfree(r);
-        }
-        xfree(pdev->vpci);
-        pdev->vpci = NULL;
-    }
+        vpci_remove_device(pdev);
 
     return rc;
 }
@@ -102,6 +107,20 @@ static void vpci_ignored_write(const struct pci_dev *pdev, 
unsigned int reg,
 {
 }
 
+uint32_t vpci_hw_read16(const struct pci_dev *pdev, unsigned int reg,
+                        void *data)
+{
+    return pci_conf_read16(pdev->seg, pdev->bus, PCI_SLOT(pdev->devfn),
+                           PCI_FUNC(pdev->devfn), reg);
+}
+
+uint32_t vpci_hw_read32(const struct pci_dev *pdev, unsigned int reg,
+                        void *data)
+{
+    return pci_conf_read32(pdev->seg, pdev->bus, PCI_SLOT(pdev->devfn),
+                           PCI_FUNC(pdev->devfn), reg);
+}
+
 int vpci_add_register(struct vpci *vpci, vpci_read_t *read_handler,
                       vpci_write_t *write_handler, unsigned int offset,
                       unsigned int size, void *data)
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 39f938644a..a452546453 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -20,6 +20,7 @@
 #include <xen/smp.h>
 #include <xen/perfc.h>
 #include <asm/atomic.h>
+#include <xen/vpci.h>
 #include <xen/wait.h>
 #include <public/xen.h>
 #include <public/domctl.h>
@@ -264,6 +265,9 @@ struct vcpu
 
     struct evtchn_fifo_vcpu *evtchn_fifo;
 
+    /* vPCI per-vCPU area, used to store data for long running operations. */
+    struct vpci_vcpu vpci;
+
     struct arch_vcpu arch;
 };
 
diff --git a/xen/include/xen/vpci.h b/xen/include/xen/vpci.h
index 9f2864fb0c..8431b2b38f 100644
--- a/xen/include/xen/vpci.h
+++ b/xen/include/xen/vpci.h
@@ -1,6 +1,8 @@
 #ifndef _XEN_VPCI_H_
 #define _XEN_VPCI_H_
 
+#ifdef CONFIG_HAS_VPCI
+
 #include <xen/pci.h>
 #include <xen/types.h>
 #include <xen/list.h>
@@ -20,6 +22,9 @@ typedef int vpci_register_init_t(struct pci_dev *dev);
 /* Add vPCI handlers to device. */
 int __must_check vpci_add_handlers(struct pci_dev *dev);
 
+/* Remove all handlers and free vpci related structures. */
+void vpci_remove_device(struct pci_dev *pdev);
+
 /* Add/remove a register handler. */
 int __must_check vpci_add_register(struct vpci *vpci,
                                    vpci_read_t *read_handler,
@@ -34,12 +39,69 @@ uint32_t vpci_read(pci_sbdf_t sbdf, unsigned int reg, 
unsigned int size);
 void vpci_write(pci_sbdf_t sbdf, unsigned int reg, unsigned int size,
                 uint32_t data);
 
+/* Passthrough handlers. */
+uint32_t vpci_hw_read16(const struct pci_dev *pdev, unsigned int reg,
+                        void *data);
+uint32_t vpci_hw_read32(const struct pci_dev *pdev, unsigned int reg,
+                        void *data);
+
+/*
+ * Check for pending vPCI operations on this vcpu. Returns true if the vcpu
+ * should not run.
+ */
+bool __must_check vpci_process_pending(struct vcpu *v);
+
 struct vpci {
     /* List of vPCI handlers for a device. */
     struct list_head handlers;
     spinlock_t lock;
+
+#ifdef __XEN__
+    /* Hide the rest of the vpci struct from the user-space test harness. */
+    struct vpci_header {
+        /* Information about the PCI BARs of this device. */
+        struct vpci_bar {
+            uint64_t addr;
+            uint64_t size;
+            enum {
+                VPCI_BAR_EMPTY,
+                VPCI_BAR_IO,
+                VPCI_BAR_MEM32,
+                VPCI_BAR_MEM64_LO,
+                VPCI_BAR_MEM64_HI,
+                VPCI_BAR_ROM,
+            } type;
+            bool prefetchable : 1;
+            /* Store whether the BAR is mapped into guest p2m. */
+            bool enabled      : 1;
+#define PCI_HEADER_NORMAL_NR_BARS        6
+#define PCI_HEADER_BRIDGE_NR_BARS        2
+        } bars[PCI_HEADER_NORMAL_NR_BARS + 1];
+        /* At most 6 BARS + 1 expansion ROM BAR. */
+
+        /*
+         * Store whether the ROM enable bit is set (doesn't imply ROM BAR
+         * is mapped into guest p2m) if there's a ROM BAR on the device.
+         */
+        bool rom_enabled      : 1;
+        /* FIXME: currently there's no support for SR-IOV. */
+    } header;
+#endif
+};
+
+struct vpci_vcpu {
+    /* Per-vcpu structure to store state while {un}mapping of PCI BARs. */
+    struct rangeset *mem;
+    struct pci_dev *pdev;
+    bool map : 1;
+    bool rom : 1;
 };
 
+#else /* !CONFIG_HAS_VPCI */
+struct vpci_vcpu {
+};
+#endif
+
 #endif
 
 /*
-- 
2.16.2


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