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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86/mm/shadow: split out HVM only code
commit 06d473a135635ab388151d1918401908f67fdb57
Author: Wei Liu <wei.liu2@xxxxxxxxxx>
AuthorDate: Fri Aug 17 11:03:24 2018 +0100
Commit: Wei Liu <wei.liu2@xxxxxxxxxx>
CommitDate: Sun Aug 26 11:01:03 2018 +0100
x86/mm/shadow: split out HVM only code
Move the code previously enclosed in CONFIG_HVM into its own file.
Note that although some code explicitly check is_hvm_*, which hints it
can be used for PV too, I can't find a code path that would be the
case.
Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
Reviewed-by: Tim Deegan <tim@xxxxxxx>
---
xen/arch/x86/mm/shadow/Makefile | 1 +
xen/arch/x86/mm/shadow/common.c | 542 +------------------------------------
xen/arch/x86/mm/shadow/hvm.c | 583 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 589 insertions(+), 537 deletions(-)
diff --git a/xen/arch/x86/mm/shadow/Makefile b/xen/arch/x86/mm/shadow/Makefile
index bcb23d2cd7..72658f3fc6 100644
--- a/xen/arch/x86/mm/shadow/Makefile
+++ b/xen/arch/x86/mm/shadow/Makefile
@@ -1,5 +1,6 @@
ifeq ($(CONFIG_SHADOW_PAGING),y)
obj-y += common.o guest_2.o guest_3.o guest_4.o
+obj-$(CONFIG_HVM) += hvm.o
else
obj-y += none.o
endif
diff --git a/xen/arch/x86/mm/shadow/common.c b/xen/arch/x86/mm/shadow/common.c
index b834921f46..1930a1d120 100644
--- a/xen/arch/x86/mm/shadow/common.c
+++ b/xen/arch/x86/mm/shadow/common.c
@@ -114,273 +114,16 @@ __initcall(shadow_audit_key_init);
#ifdef CONFIG_HVM
-/**************************************************************************/
-/* x86 emulator support for the shadow code
- */
-
-/*
- * Returns a mapped pointer to write to, or one of the following error
- * indicators.
- */
-#define MAPPING_UNHANDLEABLE ERR_PTR(~(long)X86EMUL_UNHANDLEABLE)
-#define MAPPING_EXCEPTION ERR_PTR(~(long)X86EMUL_EXCEPTION)
-#define MAPPING_SILENT_FAIL ERR_PTR(~(long)X86EMUL_OKAY)
-static void *sh_emulate_map_dest(struct vcpu *v, unsigned long vaddr,
- unsigned int bytes,
- struct sh_emulate_ctxt *sh_ctxt);
-static void sh_emulate_unmap_dest(struct vcpu *v, void *addr,
- unsigned int bytes,
- struct sh_emulate_ctxt *sh_ctxt);
-
-/*
- * Callers which pass a known in-range x86_segment can rely on the return
- * pointer being valid. Other callers must explicitly check for errors.
- */
-static struct segment_register *hvm_get_seg_reg(
- enum x86_segment seg, struct sh_emulate_ctxt *sh_ctxt)
-{
- unsigned int idx = seg;
- struct segment_register *seg_reg;
-
- if ( idx >= ARRAY_SIZE(sh_ctxt->seg_reg) )
- return ERR_PTR(-X86EMUL_UNHANDLEABLE);
-
- seg_reg = &sh_ctxt->seg_reg[idx];
- if ( !__test_and_set_bit(idx, &sh_ctxt->valid_seg_regs) )
- hvm_get_segment_register(current, idx, seg_reg);
- return seg_reg;
-}
-
-static int hvm_translate_virtual_addr(
+extern const struct x86_emulate_ops hvm_shadow_emulator_ops;
+extern struct segment_register *hvm_get_seg_reg(
+ enum x86_segment seg, struct sh_emulate_ctxt *sh_ctxt);
+extern int hvm_translate_virtual_addr(
enum x86_segment seg,
unsigned long offset,
unsigned int bytes,
enum hvm_access_type access_type,
struct sh_emulate_ctxt *sh_ctxt,
- unsigned long *linear)
-{
- const struct segment_register *reg;
- int okay;
-
- reg = hvm_get_seg_reg(seg, sh_ctxt);
- if ( IS_ERR(reg) )
- return -PTR_ERR(reg);
-
- okay = hvm_virtual_to_linear_addr(
- seg, reg, offset, bytes, access_type,
- hvm_get_seg_reg(x86_seg_cs, sh_ctxt), linear);
-
- if ( !okay )
- {
- /*
- * Leave exception injection to the caller for non-user segments: We
- * neither know the exact error code to be used, nor can we easily
- * determine the kind of exception (#GP or #TS) in that case.
- */
- if ( is_x86_user_segment(seg) )
- x86_emul_hw_exception(
- (seg == x86_seg_ss) ? TRAP_stack_error : TRAP_gp_fault,
- 0, &sh_ctxt->ctxt);
- return X86EMUL_EXCEPTION;
- }
-
- return 0;
-}
-
-static int
-hvm_read(enum x86_segment seg,
- unsigned long offset,
- void *p_data,
- unsigned int bytes,
- enum hvm_access_type access_type,
- struct sh_emulate_ctxt *sh_ctxt)
-{
- pagefault_info_t pfinfo;
- unsigned long addr;
- int rc;
-
- rc = hvm_translate_virtual_addr(
- seg, offset, bytes, access_type, sh_ctxt, &addr);
- if ( rc || !bytes )
- return rc;
-
- if ( access_type == hvm_access_insn_fetch )
- rc = hvm_fetch_from_guest_linear(p_data, addr, bytes, 0, &pfinfo);
- else
- rc = hvm_copy_from_guest_linear(p_data, addr, bytes, 0, &pfinfo);
-
- switch ( rc )
- {
- case HVMTRANS_okay:
- return X86EMUL_OKAY;
- case HVMTRANS_bad_linear_to_gfn:
- x86_emul_pagefault(pfinfo.ec, pfinfo.linear, &sh_ctxt->ctxt);
- return X86EMUL_EXCEPTION;
- case HVMTRANS_bad_gfn_to_mfn:
- case HVMTRANS_unhandleable:
- return X86EMUL_UNHANDLEABLE;
- case HVMTRANS_gfn_paged_out:
- case HVMTRANS_gfn_shared:
- return X86EMUL_RETRY;
- }
-
- BUG();
- return X86EMUL_UNHANDLEABLE;
-}
-
-static int
-hvm_emulate_read(enum x86_segment seg,
- unsigned long offset,
- void *p_data,
- unsigned int bytes,
- struct x86_emulate_ctxt *ctxt)
-{
- if ( !is_x86_user_segment(seg) )
- return X86EMUL_UNHANDLEABLE;
- return hvm_read(seg, offset, p_data, bytes, hvm_access_read,
- container_of(ctxt, struct sh_emulate_ctxt, ctxt));
-}
-
-static int
-hvm_emulate_insn_fetch(enum x86_segment seg,
- unsigned long offset,
- void *p_data,
- unsigned int bytes,
- struct x86_emulate_ctxt *ctxt)
-{
- struct sh_emulate_ctxt *sh_ctxt =
- container_of(ctxt, struct sh_emulate_ctxt, ctxt);
- unsigned int insn_off = offset - sh_ctxt->insn_buf_eip;
-
- ASSERT(seg == x86_seg_cs);
-
- /* Fall back if requested bytes are not in the prefetch cache. */
- if ( unlikely((insn_off + bytes) > sh_ctxt->insn_buf_bytes) )
- return hvm_read(seg, offset, p_data, bytes,
- hvm_access_insn_fetch, sh_ctxt);
-
- /* Hit the cache. Simple memcpy. */
- memcpy(p_data, &sh_ctxt->insn_buf[insn_off], bytes);
- return X86EMUL_OKAY;
-}
-
-static int
-hvm_emulate_write(enum x86_segment seg,
- unsigned long offset,
- void *p_data,
- unsigned int bytes,
- struct x86_emulate_ctxt *ctxt)
-{
- struct sh_emulate_ctxt *sh_ctxt =
- container_of(ctxt, struct sh_emulate_ctxt, ctxt);
- struct vcpu *v = current;
- unsigned long addr;
- void *ptr;
- int rc;
-
- /* How many emulations could we save if we unshadowed on stack writes? */
- if ( seg == x86_seg_ss )
- perfc_incr(shadow_fault_emulate_stack);
-
- rc = hvm_translate_virtual_addr(
- seg, offset, bytes, hvm_access_write, sh_ctxt, &addr);
- if ( rc || !bytes )
- return rc;
-
- /* Unaligned writes are only acceptable on HVM */
- if ( (addr & (bytes - 1)) && !is_hvm_vcpu(v) )
- return X86EMUL_UNHANDLEABLE;
-
- ptr = sh_emulate_map_dest(v, addr, bytes, sh_ctxt);
- if ( IS_ERR(ptr) )
- return ~PTR_ERR(ptr);
-
- paging_lock(v->domain);
- memcpy(ptr, p_data, bytes);
-
- if ( tb_init_done )
- v->arch.paging.mode->shadow.trace_emul_write_val(ptr, addr,
- p_data, bytes);
-
- sh_emulate_unmap_dest(v, ptr, bytes, sh_ctxt);
- shadow_audit_tables(v);
- paging_unlock(v->domain);
-
- return X86EMUL_OKAY;
-}
-
-static int
-hvm_emulate_cmpxchg(enum x86_segment seg,
- unsigned long offset,
- void *p_old,
- void *p_new,
- unsigned int bytes,
- bool lock,
- struct x86_emulate_ctxt *ctxt)
-{
- struct sh_emulate_ctxt *sh_ctxt =
- container_of(ctxt, struct sh_emulate_ctxt, ctxt);
- struct vcpu *v = current;
- unsigned long addr, old, new, prev;
- void *ptr;
- int rc;
-
- if ( bytes > sizeof(long) )
- return X86EMUL_UNHANDLEABLE;
-
- rc = hvm_translate_virtual_addr(
- seg, offset, bytes, hvm_access_write, sh_ctxt, &addr);
- if ( rc )
- return rc;
-
- /* Unaligned writes are only acceptable on HVM */
- if ( (addr & (bytes - 1)) && !is_hvm_vcpu(v) )
- return X86EMUL_UNHANDLEABLE;
-
- ptr = sh_emulate_map_dest(v, addr, bytes, sh_ctxt);
- if ( IS_ERR(ptr) )
- return ~PTR_ERR(ptr);
-
- old = new = 0;
- memcpy(&old, p_old, bytes);
- memcpy(&new, p_new, bytes);
-
- paging_lock(v->domain);
- switch ( bytes )
- {
- case 1: prev = cmpxchg((uint8_t *)ptr, old, new); break;
- case 2: prev = cmpxchg((uint16_t *)ptr, old, new); break;
- case 4: prev = cmpxchg((uint32_t *)ptr, old, new); break;
- case 8: prev = cmpxchg((uint64_t *)ptr, old, new); break;
- default:
- SHADOW_PRINTK("cmpxchg size %u is not supported\n", bytes);
- prev = ~old;
- }
-
- if ( prev != old )
- {
- memcpy(p_old, &prev, bytes);
- rc = X86EMUL_CMPXCHG_FAILED;
- }
-
- SHADOW_DEBUG(EMULATE,
- "va %#lx was %#lx expected %#lx wanted %#lx now %#lx bytes
%u\n",
- addr, prev, old, new, *(unsigned long *)ptr, bytes);
-
- sh_emulate_unmap_dest(v, ptr, bytes, sh_ctxt);
- shadow_audit_tables(v);
- paging_unlock(v->domain);
-
- return rc;
-}
-
-static const struct x86_emulate_ops hvm_shadow_emulator_ops = {
- .read = hvm_emulate_read,
- .insn_fetch = hvm_emulate_insn_fetch,
- .write = hvm_emulate_write,
- .cmpxchg = hvm_emulate_cmpxchg,
- .cpuid = hvmemul_cpuid,
-};
+ unsigned long *linear);
#endif
const struct x86_emulate_ops *shadow_init_emulation(
@@ -1697,281 +1440,6 @@ static unsigned int shadow_get_allocation(struct domain
*d)
+ ((pg & ((1 << (20 - PAGE_SHIFT)) - 1)) ? 1 : 0));
}
-#ifdef CONFIG_HVM
-/**************************************************************************/
-/* Handling guest writes to pagetables. */
-
-/*
- * Translate a VA to an MFN, injecting a page-fault if we fail. If the
- * mapping succeeds, a reference will be held on the underlying page.
- */
-#define BAD_GVA_TO_GFN (~0UL)
-#define BAD_GFN_TO_MFN (~1UL)
-#define READONLY_GFN (~2UL)
-static mfn_t emulate_gva_to_mfn(struct vcpu *v, unsigned long vaddr,
- struct sh_emulate_ctxt *sh_ctxt)
-{
- unsigned long gfn;
- struct page_info *page;
- mfn_t mfn;
- p2m_type_t p2mt;
- uint32_t pfec = PFEC_page_present | PFEC_write_access;
-
- /* Translate the VA to a GFN. */
- gfn = paging_get_hostmode(v)->gva_to_gfn(v, NULL, vaddr, &pfec);
- if ( gfn == gfn_x(INVALID_GFN) )
- {
- x86_emul_pagefault(pfec, vaddr, &sh_ctxt->ctxt);
-
- return _mfn(BAD_GVA_TO_GFN);
- }
-
- /* Translate the GFN to an MFN. */
- ASSERT(!paging_locked_by_me(v->domain));
-
- page = get_page_from_gfn(v->domain, gfn, &p2mt, P2M_ALLOC);
-
- /* Sanity checking. */
- if ( page == NULL )
- {
- return _mfn(BAD_GFN_TO_MFN);
- }
- if ( p2m_is_discard_write(p2mt) )
- {
- put_page(page);
- return _mfn(READONLY_GFN);
- }
- if ( !p2m_is_ram(p2mt) )
- {
- put_page(page);
- return _mfn(BAD_GFN_TO_MFN);
- }
- mfn = page_to_mfn(page);
- ASSERT(mfn_valid(mfn));
-
- v->arch.paging.last_write_was_pt = !!sh_mfn_is_a_page_table(mfn);
-
- return mfn;
-}
-
-/*
- * Check that the user is allowed to perform this write. If a mapping is
- * returned, page references will be held on sh_ctxt->mfn[0] and
- * sh_ctxt->mfn[1] iff !INVALID_MFN.
- */
-static void *sh_emulate_map_dest(struct vcpu *v, unsigned long vaddr,
- unsigned int bytes,
- struct sh_emulate_ctxt *sh_ctxt)
-{
- struct domain *d = v->domain;
- void *map;
-
-#ifndef NDEBUG
- /* We don't emulate user-mode writes to page tables. */
- if ( is_hvm_domain(d) ? hvm_get_cpl(v) == 3
- : !guest_kernel_mode(v, guest_cpu_user_regs()) )
- {
- gdprintk(XENLOG_DEBUG, "User-mode write to pagetable reached "
- "emulate_map_dest(). This should never happen!\n");
- return MAPPING_UNHANDLEABLE;
- }
-#endif
-
- sh_ctxt->mfn[0] = emulate_gva_to_mfn(v, vaddr, sh_ctxt);
- if ( !mfn_valid(sh_ctxt->mfn[0]) )
- {
- switch ( mfn_x(sh_ctxt->mfn[0]) )
- {
- case BAD_GVA_TO_GFN: return MAPPING_EXCEPTION;
- case READONLY_GFN: return MAPPING_SILENT_FAIL;
- default: return MAPPING_UNHANDLEABLE;
- }
- }
-
- /* Unaligned writes mean probably this isn't a pagetable. */
- if ( vaddr & (bytes - 1) )
- sh_remove_shadows(d, sh_ctxt->mfn[0], 0, 0 /* Slow, can fail. */ );
-
- if ( likely(((vaddr + bytes - 1) & PAGE_MASK) == (vaddr & PAGE_MASK)) )
- {
- /* Whole write fits on a single page. */
- sh_ctxt->mfn[1] = INVALID_MFN;
- map = map_domain_page(sh_ctxt->mfn[0]) + (vaddr & ~PAGE_MASK);
- }
- else if ( !is_hvm_domain(d) )
- {
- /*
- * Cross-page emulated writes are only supported for HVM guests;
- * PV guests ought to know better.
- */
- put_page(mfn_to_page(sh_ctxt->mfn[0]));
- return MAPPING_UNHANDLEABLE;
- }
- else
- {
- /* This write crosses a page boundary. Translate the second page. */
- sh_ctxt->mfn[1] = emulate_gva_to_mfn(
- v, (vaddr + bytes - 1) & PAGE_MASK, sh_ctxt);
- if ( !mfn_valid(sh_ctxt->mfn[1]) )
- {
- put_page(mfn_to_page(sh_ctxt->mfn[0]));
- switch ( mfn_x(sh_ctxt->mfn[1]) )
- {
- case BAD_GVA_TO_GFN: return MAPPING_EXCEPTION;
- case READONLY_GFN: return MAPPING_SILENT_FAIL;
- default: return MAPPING_UNHANDLEABLE;
- }
- }
-
- /* Cross-page writes mean probably not a pagetable. */
- sh_remove_shadows(d, sh_ctxt->mfn[1], 0, 0 /* Slow, can fail. */ );
-
- map = vmap(sh_ctxt->mfn, 2);
- if ( !map )
- {
- put_page(mfn_to_page(sh_ctxt->mfn[0]));
- put_page(mfn_to_page(sh_ctxt->mfn[1]));
- return MAPPING_UNHANDLEABLE;
- }
- map += (vaddr & ~PAGE_MASK);
- }
-
-#if (SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY)
- /*
- * Remember if the bottom bit was clear, so we can choose not to run
- * the change through the verify code if it's still clear afterwards.
- */
- sh_ctxt->low_bit_was_clear = map != NULL && !(*(u8 *)map & _PAGE_PRESENT);
-#endif
-
- return map;
-}
-
-/*
- * Optimization: If we see two emulated writes of zeros to the same
- * page-table without another kind of page fault in between, we guess
- * that this is a batch of changes (for process destruction) and
- * unshadow the page so we don't take a pagefault on every entry. This
- * should also make finding writeable mappings of pagetables much
- * easier.
- *
- * Look to see if this is the second emulated write in a row to this
- * page, and unshadow if it is.
- */
-static inline void check_for_early_unshadow(struct vcpu *v, mfn_t gmfn)
-{
-#if SHADOW_OPTIMIZATIONS & SHOPT_EARLY_UNSHADOW
- struct domain *d = v->domain;
-
- /*
- * If the domain has never made a "dying" op, use the two-writes
- * heuristic; otherwise, unshadow as soon as we write a zero for a dying
- * process.
- *
- * Don't bother trying to unshadow if it's not a PT, or if it's > l1.
- */
- if ( ( v->arch.paging.shadow.pagetable_dying
- || ( !d->arch.paging.shadow.pagetable_dying_op
- && v->arch.paging.shadow.last_emulated_mfn_for_unshadow ==
mfn_x(gmfn) ) )
- && sh_mfn_is_a_page_table(gmfn)
- && (!d->arch.paging.shadow.pagetable_dying_op ||
- !(mfn_to_page(gmfn)->shadow_flags
- & (SHF_L2_32|SHF_L2_PAE|SHF_L2H_PAE|SHF_L4_64))) )
- {
- perfc_incr(shadow_early_unshadow);
- sh_remove_shadows(d, gmfn, 1, 0 /* Fast, can fail to unshadow */ );
- TRACE_SHADOW_PATH_FLAG(TRCE_SFLAG_EARLY_UNSHADOW);
- }
- v->arch.paging.shadow.last_emulated_mfn_for_unshadow = mfn_x(gmfn);
-#endif
-}
-
-/*
- * Tidy up after the emulated write: mark pages dirty, verify the new
- * contents, and undo the mapping.
- */
-static void sh_emulate_unmap_dest(struct vcpu *v, void *addr,
- unsigned int bytes,
- struct sh_emulate_ctxt *sh_ctxt)
-{
- u32 b1 = bytes, b2 = 0, shflags;
-
- ASSERT(mfn_valid(sh_ctxt->mfn[0]));
-
- /* If we are writing lots of PTE-aligned zeros, might want to unshadow */
- if ( likely(bytes >= 4) && (*(u32 *)addr == 0) )
- {
- if ( !((unsigned long)addr & (sh_ctxt->pte_size - 1)) )
- check_for_early_unshadow(v, sh_ctxt->mfn[0]);
- /*
- * Don't reset the heuristic if we're writing zeros at non-aligned
- * addresses, otherwise it doesn't catch REP MOVSD on PAE guests.
- */
- }
- else
- sh_reset_early_unshadow(v);
-
- /*
- * We can avoid re-verifying the page contents after the write if:
- * - it was no larger than the PTE type of this pagetable;
- * - it was aligned to the PTE boundaries; and
- * - _PAGE_PRESENT was clear before and after the write.
- */
- shflags = mfn_to_page(sh_ctxt->mfn[0])->shadow_flags;
-#if (SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY)
- if ( sh_ctxt->low_bit_was_clear
- && !(*(u8 *)addr & _PAGE_PRESENT)
- && ((!(shflags & SHF_32)
- /*
- * Not shadowed 32-bit: aligned 64-bit writes that leave
- * the present bit unset are safe to ignore.
- */
- && ((unsigned long)addr & 7) == 0
- && bytes <= 8)
- ||
- (!(shflags & (SHF_PAE|SHF_64))
- /*
- * Not shadowed PAE/64-bit: aligned 32-bit writes that
- * leave the present bit unset are safe to ignore.
- */
- && ((unsigned long)addr & 3) == 0
- && bytes <= 4)) )
- {
- /* Writes with this alignment constraint can't possibly cross pages. */
- ASSERT(!mfn_valid(sh_ctxt->mfn[1]));
- }
- else
-#endif /* SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY */
- {
- if ( unlikely(mfn_valid(sh_ctxt->mfn[1])) )
- {
- /* Validate as two writes, one to each page. */
- b1 = PAGE_SIZE - (((unsigned long)addr) & ~PAGE_MASK);
- b2 = bytes - b1;
- ASSERT(b2 < bytes);
- }
- if ( likely(b1 > 0) )
- sh_validate_guest_pt_write(v, sh_ctxt->mfn[0], addr, b1);
- if ( unlikely(b2 > 0) )
- sh_validate_guest_pt_write(v, sh_ctxt->mfn[1], addr + b1, b2);
- }
-
- paging_mark_dirty(v->domain, sh_ctxt->mfn[0]);
- put_page(mfn_to_page(sh_ctxt->mfn[0]));
-
- if ( unlikely(mfn_valid(sh_ctxt->mfn[1])) )
- {
- paging_mark_dirty(v->domain, sh_ctxt->mfn[1]);
- put_page(mfn_to_page(sh_ctxt->mfn[1]));
- vunmap((void *)((unsigned long)addr & PAGE_MASK));
- }
- else
- unmap_domain_page(addr);
-
- atomic_inc(&v->domain->arch.paging.shadow.gtable_dirty_version);
-}
-#endif
-
/**************************************************************************/
/* Hash table for storing the guest->shadow mappings.
* The table itself is an array of pointers to shadows; the shadows are then
diff --git a/xen/arch/x86/mm/shadow/hvm.c b/xen/arch/x86/mm/shadow/hvm.c
new file mode 100644
index 0000000000..ca2763685c
--- /dev/null
+++ b/xen/arch/x86/mm/shadow/hvm.c
@@ -0,0 +1,583 @@
+
+/******************************************************************************
+ * arch/x86/mm/shadow/hvm.c
+ *
+ * Shadow code that does not need to be multiply compiled and is HVM only.
+ * Parts of this code are Copyright (c) 2006 by XenSource Inc.
+ * Parts of this code are Copyright (c) 2006 by Michael A Fetterman
+ * Parts based on earlier work by Michael A Fetterman, Ian Pratt et al.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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/domain_page.h>
+#include <xen/guest_access.h>
+#include <xen/sched.h>
+#include <xen/types.h>
+#include <xen/trace.h>
+
+#include <asm/current.h>
+#include <asm/shadow.h>
+
+#include "private.h"
+
+/**************************************************************************/
+/* x86 emulator support for the shadow code
+ */
+
+/*
+ * Returns a mapped pointer to write to, or one of the following error
+ * indicators.
+ */
+#define MAPPING_UNHANDLEABLE ERR_PTR(~(long)X86EMUL_UNHANDLEABLE)
+#define MAPPING_EXCEPTION ERR_PTR(~(long)X86EMUL_EXCEPTION)
+#define MAPPING_SILENT_FAIL ERR_PTR(~(long)X86EMUL_OKAY)
+static void *sh_emulate_map_dest(struct vcpu *v, unsigned long vaddr,
+ unsigned int bytes,
+ struct sh_emulate_ctxt *sh_ctxt);
+static void sh_emulate_unmap_dest(struct vcpu *v, void *addr,
+ unsigned int bytes,
+ struct sh_emulate_ctxt *sh_ctxt);
+
+/*
+ * Callers which pass a known in-range x86_segment can rely on the return
+ * pointer being valid. Other callers must explicitly check for errors.
+ */
+struct segment_register *hvm_get_seg_reg(
+ enum x86_segment seg, struct sh_emulate_ctxt *sh_ctxt)
+{
+ unsigned int idx = seg;
+ struct segment_register *seg_reg;
+
+ if ( idx >= ARRAY_SIZE(sh_ctxt->seg_reg) )
+ return ERR_PTR(-X86EMUL_UNHANDLEABLE);
+
+ seg_reg = &sh_ctxt->seg_reg[idx];
+ if ( !__test_and_set_bit(idx, &sh_ctxt->valid_seg_regs) )
+ hvm_get_segment_register(current, idx, seg_reg);
+ return seg_reg;
+}
+
+int hvm_translate_virtual_addr(
+ enum x86_segment seg,
+ unsigned long offset,
+ unsigned int bytes,
+ enum hvm_access_type access_type,
+ struct sh_emulate_ctxt *sh_ctxt,
+ unsigned long *linear)
+{
+ const struct segment_register *reg;
+ int okay;
+
+ reg = hvm_get_seg_reg(seg, sh_ctxt);
+ if ( IS_ERR(reg) )
+ return -PTR_ERR(reg);
+
+ okay = hvm_virtual_to_linear_addr(
+ seg, reg, offset, bytes, access_type,
+ hvm_get_seg_reg(x86_seg_cs, sh_ctxt), linear);
+
+ if ( !okay )
+ {
+ /*
+ * Leave exception injection to the caller for non-user segments: We
+ * neither know the exact error code to be used, nor can we easily
+ * determine the kind of exception (#GP or #TS) in that case.
+ */
+ if ( is_x86_user_segment(seg) )
+ x86_emul_hw_exception(
+ (seg == x86_seg_ss) ? TRAP_stack_error : TRAP_gp_fault,
+ 0, &sh_ctxt->ctxt);
+ return X86EMUL_EXCEPTION;
+ }
+
+ return 0;
+}
+
+static int
+hvm_read(enum x86_segment seg,
+ unsigned long offset,
+ void *p_data,
+ unsigned int bytes,
+ enum hvm_access_type access_type,
+ struct sh_emulate_ctxt *sh_ctxt)
+{
+ pagefault_info_t pfinfo;
+ unsigned long addr;
+ int rc;
+
+ rc = hvm_translate_virtual_addr(
+ seg, offset, bytes, access_type, sh_ctxt, &addr);
+ if ( rc || !bytes )
+ return rc;
+
+ if ( access_type == hvm_access_insn_fetch )
+ rc = hvm_fetch_from_guest_linear(p_data, addr, bytes, 0, &pfinfo);
+ else
+ rc = hvm_copy_from_guest_linear(p_data, addr, bytes, 0, &pfinfo);
+
+ switch ( rc )
+ {
+ case HVMTRANS_okay:
+ return X86EMUL_OKAY;
+ case HVMTRANS_bad_linear_to_gfn:
+ x86_emul_pagefault(pfinfo.ec, pfinfo.linear, &sh_ctxt->ctxt);
+ return X86EMUL_EXCEPTION;
+ case HVMTRANS_bad_gfn_to_mfn:
+ case HVMTRANS_unhandleable:
+ return X86EMUL_UNHANDLEABLE;
+ case HVMTRANS_gfn_paged_out:
+ case HVMTRANS_gfn_shared:
+ return X86EMUL_RETRY;
+ }
+
+ BUG();
+ return X86EMUL_UNHANDLEABLE;
+}
+
+static int
+hvm_emulate_read(enum x86_segment seg,
+ unsigned long offset,
+ void *p_data,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt)
+{
+ if ( !is_x86_user_segment(seg) )
+ return X86EMUL_UNHANDLEABLE;
+ return hvm_read(seg, offset, p_data, bytes, hvm_access_read,
+ container_of(ctxt, struct sh_emulate_ctxt, ctxt));
+}
+
+static int
+hvm_emulate_insn_fetch(enum x86_segment seg,
+ unsigned long offset,
+ void *p_data,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt)
+{
+ struct sh_emulate_ctxt *sh_ctxt =
+ container_of(ctxt, struct sh_emulate_ctxt, ctxt);
+ unsigned int insn_off = offset - sh_ctxt->insn_buf_eip;
+
+ ASSERT(seg == x86_seg_cs);
+
+ /* Fall back if requested bytes are not in the prefetch cache. */
+ if ( unlikely((insn_off + bytes) > sh_ctxt->insn_buf_bytes) )
+ return hvm_read(seg, offset, p_data, bytes,
+ hvm_access_insn_fetch, sh_ctxt);
+
+ /* Hit the cache. Simple memcpy. */
+ memcpy(p_data, &sh_ctxt->insn_buf[insn_off], bytes);
+ return X86EMUL_OKAY;
+}
+
+static int
+hvm_emulate_write(enum x86_segment seg,
+ unsigned long offset,
+ void *p_data,
+ unsigned int bytes,
+ struct x86_emulate_ctxt *ctxt)
+{
+ struct sh_emulate_ctxt *sh_ctxt =
+ container_of(ctxt, struct sh_emulate_ctxt, ctxt);
+ struct vcpu *v = current;
+ unsigned long addr;
+ void *ptr;
+ int rc;
+
+ /* How many emulations could we save if we unshadowed on stack writes? */
+ if ( seg == x86_seg_ss )
+ perfc_incr(shadow_fault_emulate_stack);
+
+ rc = hvm_translate_virtual_addr(
+ seg, offset, bytes, hvm_access_write, sh_ctxt, &addr);
+ if ( rc || !bytes )
+ return rc;
+
+ /* Unaligned writes are only acceptable on HVM */
+ if ( (addr & (bytes - 1)) && !is_hvm_vcpu(v) )
+ return X86EMUL_UNHANDLEABLE;
+
+ ptr = sh_emulate_map_dest(v, addr, bytes, sh_ctxt);
+ if ( IS_ERR(ptr) )
+ return ~PTR_ERR(ptr);
+
+ paging_lock(v->domain);
+ memcpy(ptr, p_data, bytes);
+
+ if ( tb_init_done )
+ v->arch.paging.mode->shadow.trace_emul_write_val(ptr, addr,
+ p_data, bytes);
+
+ sh_emulate_unmap_dest(v, ptr, bytes, sh_ctxt);
+ shadow_audit_tables(v);
+ paging_unlock(v->domain);
+
+ return X86EMUL_OKAY;
+}
+
+static int
+hvm_emulate_cmpxchg(enum x86_segment seg,
+ unsigned long offset,
+ void *p_old,
+ void *p_new,
+ unsigned int bytes,
+ bool lock,
+ struct x86_emulate_ctxt *ctxt)
+{
+ struct sh_emulate_ctxt *sh_ctxt =
+ container_of(ctxt, struct sh_emulate_ctxt, ctxt);
+ struct vcpu *v = current;
+ unsigned long addr, old, new, prev;
+ void *ptr;
+ int rc;
+
+ if ( bytes > sizeof(long) )
+ return X86EMUL_UNHANDLEABLE;
+
+ rc = hvm_translate_virtual_addr(
+ seg, offset, bytes, hvm_access_write, sh_ctxt, &addr);
+ if ( rc )
+ return rc;
+
+ /* Unaligned writes are only acceptable on HVM */
+ if ( (addr & (bytes - 1)) && !is_hvm_vcpu(v) )
+ return X86EMUL_UNHANDLEABLE;
+
+ ptr = sh_emulate_map_dest(v, addr, bytes, sh_ctxt);
+ if ( IS_ERR(ptr) )
+ return ~PTR_ERR(ptr);
+
+ old = new = 0;
+ memcpy(&old, p_old, bytes);
+ memcpy(&new, p_new, bytes);
+
+ paging_lock(v->domain);
+ switch ( bytes )
+ {
+ case 1: prev = cmpxchg((uint8_t *)ptr, old, new); break;
+ case 2: prev = cmpxchg((uint16_t *)ptr, old, new); break;
+ case 4: prev = cmpxchg((uint32_t *)ptr, old, new); break;
+ case 8: prev = cmpxchg((uint64_t *)ptr, old, new); break;
+ default:
+ SHADOW_PRINTK("cmpxchg size %u is not supported\n", bytes);
+ prev = ~old;
+ }
+
+ if ( prev != old )
+ {
+ memcpy(p_old, &prev, bytes);
+ rc = X86EMUL_CMPXCHG_FAILED;
+ }
+
+ SHADOW_DEBUG(EMULATE,
+ "va %#lx was %#lx expected %#lx wanted %#lx now %#lx bytes
%u\n",
+ addr, prev, old, new, *(unsigned long *)ptr, bytes);
+
+ sh_emulate_unmap_dest(v, ptr, bytes, sh_ctxt);
+ shadow_audit_tables(v);
+ paging_unlock(v->domain);
+
+ return rc;
+}
+
+const struct x86_emulate_ops hvm_shadow_emulator_ops = {
+ .read = hvm_emulate_read,
+ .insn_fetch = hvm_emulate_insn_fetch,
+ .write = hvm_emulate_write,
+ .cmpxchg = hvm_emulate_cmpxchg,
+ .cpuid = hvmemul_cpuid,
+};
+
+/**************************************************************************/
+/* Handling guest writes to pagetables. */
+
+/*
+ * Translate a VA to an MFN, injecting a page-fault if we fail. If the
+ * mapping succeeds, a reference will be held on the underlying page.
+ */
+#define BAD_GVA_TO_GFN (~0UL)
+#define BAD_GFN_TO_MFN (~1UL)
+#define READONLY_GFN (~2UL)
+static mfn_t emulate_gva_to_mfn(struct vcpu *v, unsigned long vaddr,
+ struct sh_emulate_ctxt *sh_ctxt)
+{
+ unsigned long gfn;
+ struct page_info *page;
+ mfn_t mfn;
+ p2m_type_t p2mt;
+ uint32_t pfec = PFEC_page_present | PFEC_write_access;
+
+ /* Translate the VA to a GFN. */
+ gfn = paging_get_hostmode(v)->gva_to_gfn(v, NULL, vaddr, &pfec);
+ if ( gfn == gfn_x(INVALID_GFN) )
+ {
+ x86_emul_pagefault(pfec, vaddr, &sh_ctxt->ctxt);
+
+ return _mfn(BAD_GVA_TO_GFN);
+ }
+
+ /* Translate the GFN to an MFN. */
+ ASSERT(!paging_locked_by_me(v->domain));
+
+ page = get_page_from_gfn(v->domain, gfn, &p2mt, P2M_ALLOC);
+
+ /* Sanity checking. */
+ if ( page == NULL )
+ {
+ return _mfn(BAD_GFN_TO_MFN);
+ }
+ if ( p2m_is_discard_write(p2mt) )
+ {
+ put_page(page);
+ return _mfn(READONLY_GFN);
+ }
+ if ( !p2m_is_ram(p2mt) )
+ {
+ put_page(page);
+ return _mfn(BAD_GFN_TO_MFN);
+ }
+ mfn = page_to_mfn(page);
+ ASSERT(mfn_valid(mfn));
+
+ v->arch.paging.last_write_was_pt = !!sh_mfn_is_a_page_table(mfn);
+
+ return mfn;
+}
+
+/*
+ * Check that the user is allowed to perform this write. If a mapping is
+ * returned, page references will be held on sh_ctxt->mfn[0] and
+ * sh_ctxt->mfn[1] iff !INVALID_MFN.
+ */
+static void *sh_emulate_map_dest(struct vcpu *v, unsigned long vaddr,
+ unsigned int bytes,
+ struct sh_emulate_ctxt *sh_ctxt)
+{
+ struct domain *d = v->domain;
+ void *map;
+
+#ifndef NDEBUG
+ /* We don't emulate user-mode writes to page tables. */
+ if ( is_hvm_domain(d) ? hvm_get_cpl(v) == 3
+ : !guest_kernel_mode(v, guest_cpu_user_regs()) )
+ {
+ gdprintk(XENLOG_DEBUG, "User-mode write to pagetable reached "
+ "emulate_map_dest(). This should never happen!\n");
+ return MAPPING_UNHANDLEABLE;
+ }
+#endif
+
+ sh_ctxt->mfn[0] = emulate_gva_to_mfn(v, vaddr, sh_ctxt);
+ if ( !mfn_valid(sh_ctxt->mfn[0]) )
+ {
+ switch ( mfn_x(sh_ctxt->mfn[0]) )
+ {
+ case BAD_GVA_TO_GFN: return MAPPING_EXCEPTION;
+ case READONLY_GFN: return MAPPING_SILENT_FAIL;
+ default: return MAPPING_UNHANDLEABLE;
+ }
+ }
+
+ /* Unaligned writes mean probably this isn't a pagetable. */
+ if ( vaddr & (bytes - 1) )
+ sh_remove_shadows(d, sh_ctxt->mfn[0], 0, 0 /* Slow, can fail. */ );
+
+ if ( likely(((vaddr + bytes - 1) & PAGE_MASK) == (vaddr & PAGE_MASK)) )
+ {
+ /* Whole write fits on a single page. */
+ sh_ctxt->mfn[1] = INVALID_MFN;
+ map = map_domain_page(sh_ctxt->mfn[0]) + (vaddr & ~PAGE_MASK);
+ }
+ else if ( !is_hvm_domain(d) )
+ {
+ /*
+ * Cross-page emulated writes are only supported for HVM guests;
+ * PV guests ought to know better.
+ */
+ put_page(mfn_to_page(sh_ctxt->mfn[0]));
+ return MAPPING_UNHANDLEABLE;
+ }
+ else
+ {
+ /* This write crosses a page boundary. Translate the second page. */
+ sh_ctxt->mfn[1] = emulate_gva_to_mfn(
+ v, (vaddr + bytes - 1) & PAGE_MASK, sh_ctxt);
+ if ( !mfn_valid(sh_ctxt->mfn[1]) )
+ {
+ put_page(mfn_to_page(sh_ctxt->mfn[0]));
+ switch ( mfn_x(sh_ctxt->mfn[1]) )
+ {
+ case BAD_GVA_TO_GFN: return MAPPING_EXCEPTION;
+ case READONLY_GFN: return MAPPING_SILENT_FAIL;
+ default: return MAPPING_UNHANDLEABLE;
+ }
+ }
+
+ /* Cross-page writes mean probably not a pagetable. */
+ sh_remove_shadows(d, sh_ctxt->mfn[1], 0, 0 /* Slow, can fail. */ );
+
+ map = vmap(sh_ctxt->mfn, 2);
+ if ( !map )
+ {
+ put_page(mfn_to_page(sh_ctxt->mfn[0]));
+ put_page(mfn_to_page(sh_ctxt->mfn[1]));
+ return MAPPING_UNHANDLEABLE;
+ }
+ map += (vaddr & ~PAGE_MASK);
+ }
+
+#if (SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY)
+ /*
+ * Remember if the bottom bit was clear, so we can choose not to run
+ * the change through the verify code if it's still clear afterwards.
+ */
+ sh_ctxt->low_bit_was_clear = map != NULL && !(*(u8 *)map & _PAGE_PRESENT);
+#endif
+
+ return map;
+}
+
+/*
+ * Optimization: If we see two emulated writes of zeros to the same
+ * page-table without another kind of page fault in between, we guess
+ * that this is a batch of changes (for process destruction) and
+ * unshadow the page so we don't take a pagefault on every entry. This
+ * should also make finding writeable mappings of pagetables much
+ * easier.
+ *
+ * Look to see if this is the second emulated write in a row to this
+ * page, and unshadow if it is.
+ */
+static inline void check_for_early_unshadow(struct vcpu *v, mfn_t gmfn)
+{
+#if SHADOW_OPTIMIZATIONS & SHOPT_EARLY_UNSHADOW
+ struct domain *d = v->domain;
+
+ /*
+ * If the domain has never made a "dying" op, use the two-writes
+ * heuristic; otherwise, unshadow as soon as we write a zero for a dying
+ * process.
+ *
+ * Don't bother trying to unshadow if it's not a PT, or if it's > l1.
+ */
+ if ( ( v->arch.paging.shadow.pagetable_dying
+ || ( !d->arch.paging.shadow.pagetable_dying_op
+ && v->arch.paging.shadow.last_emulated_mfn_for_unshadow ==
mfn_x(gmfn) ) )
+ && sh_mfn_is_a_page_table(gmfn)
+ && (!d->arch.paging.shadow.pagetable_dying_op ||
+ !(mfn_to_page(gmfn)->shadow_flags
+ & (SHF_L2_32|SHF_L2_PAE|SHF_L2H_PAE|SHF_L4_64))) )
+ {
+ perfc_incr(shadow_early_unshadow);
+ sh_remove_shadows(d, gmfn, 1, 0 /* Fast, can fail to unshadow */ );
+ TRACE_SHADOW_PATH_FLAG(TRCE_SFLAG_EARLY_UNSHADOW);
+ }
+ v->arch.paging.shadow.last_emulated_mfn_for_unshadow = mfn_x(gmfn);
+#endif
+}
+
+/*
+ * Tidy up after the emulated write: mark pages dirty, verify the new
+ * contents, and undo the mapping.
+ */
+static void sh_emulate_unmap_dest(struct vcpu *v, void *addr,
+ unsigned int bytes,
+ struct sh_emulate_ctxt *sh_ctxt)
+{
+ u32 b1 = bytes, b2 = 0, shflags;
+
+ ASSERT(mfn_valid(sh_ctxt->mfn[0]));
+
+ /* If we are writing lots of PTE-aligned zeros, might want to unshadow */
+ if ( likely(bytes >= 4) && (*(u32 *)addr == 0) )
+ {
+ if ( !((unsigned long)addr & (sh_ctxt->pte_size - 1)) )
+ check_for_early_unshadow(v, sh_ctxt->mfn[0]);
+ /*
+ * Don't reset the heuristic if we're writing zeros at non-aligned
+ * addresses, otherwise it doesn't catch REP MOVSD on PAE guests.
+ */
+ }
+ else
+ sh_reset_early_unshadow(v);
+
+ /*
+ * We can avoid re-verifying the page contents after the write if:
+ * - it was no larger than the PTE type of this pagetable;
+ * - it was aligned to the PTE boundaries; and
+ * - _PAGE_PRESENT was clear before and after the write.
+ */
+ shflags = mfn_to_page(sh_ctxt->mfn[0])->shadow_flags;
+#if (SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY)
+ if ( sh_ctxt->low_bit_was_clear
+ && !(*(u8 *)addr & _PAGE_PRESENT)
+ && ((!(shflags & SHF_32)
+ /*
+ * Not shadowed 32-bit: aligned 64-bit writes that leave
+ * the present bit unset are safe to ignore.
+ */
+ && ((unsigned long)addr & 7) == 0
+ && bytes <= 8)
+ ||
+ (!(shflags & (SHF_PAE|SHF_64))
+ /*
+ * Not shadowed PAE/64-bit: aligned 32-bit writes that
+ * leave the present bit unset are safe to ignore.
+ */
+ && ((unsigned long)addr & 3) == 0
+ && bytes <= 4)) )
+ {
+ /* Writes with this alignment constraint can't possibly cross pages. */
+ ASSERT(!mfn_valid(sh_ctxt->mfn[1]));
+ }
+ else
+#endif /* SHADOW_OPTIMIZATIONS & SHOPT_SKIP_VERIFY */
+ {
+ if ( unlikely(mfn_valid(sh_ctxt->mfn[1])) )
+ {
+ /* Validate as two writes, one to each page. */
+ b1 = PAGE_SIZE - (((unsigned long)addr) & ~PAGE_MASK);
+ b2 = bytes - b1;
+ ASSERT(b2 < bytes);
+ }
+ if ( likely(b1 > 0) )
+ sh_validate_guest_pt_write(v, sh_ctxt->mfn[0], addr, b1);
+ if ( unlikely(b2 > 0) )
+ sh_validate_guest_pt_write(v, sh_ctxt->mfn[1], addr + b1, b2);
+ }
+
+ paging_mark_dirty(v->domain, sh_ctxt->mfn[0]);
+ put_page(mfn_to_page(sh_ctxt->mfn[0]));
+
+ if ( unlikely(mfn_valid(sh_ctxt->mfn[1])) )
+ {
+ paging_mark_dirty(v->domain, sh_ctxt->mfn[1]);
+ put_page(mfn_to_page(sh_ctxt->mfn[1]));
+ vunmap((void *)((unsigned long)addr & PAGE_MASK));
+ }
+ else
+ unmap_domain_page(addr);
+
+ atomic_inc(&v->domain->arch.paging.shadow.gtable_dirty_version);
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
--
generated by git-patchbot for /home/xen/git/xen.git#master
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