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-rw-r--r--arch/x86/include/asm/kvm_host.h37
-rw-r--r--arch/x86/kvm/mmu/mmu.c5
-rw-r--r--arch/x86/kvm/mmu/mmu_internal.h12
-rw-r--r--arch/x86/kvm/mmu/paging_tmpl.h4
-rw-r--r--arch/x86/kvm/x86.c15
5 files changed, 37 insertions, 36 deletions
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 808c292ad3f4..a45de1118a42 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -947,23 +947,6 @@ struct kvm_vcpu_arch {
u64 msr_kvm_poll_control;
- /*
- * Indicates the guest is trying to write a gfn that contains one or
- * more of the PTEs used to translate the write itself, i.e. the access
- * is changing its own translation in the guest page tables. KVM exits
- * to userspace if emulation of the faulting instruction fails and this
- * flag is set, as KVM cannot make forward progress.
- *
- * If emulation fails for a write to guest page tables, KVM unprotects
- * (zaps) the shadow page for the target gfn and resumes the guest to
- * retry the non-emulatable instruction (on hardware). Unprotecting the
- * gfn doesn't allow forward progress for a self-changing access because
- * doing so also zaps the translation for the gfn, i.e. retrying the
- * instruction will hit a !PRESENT fault, which results in a new shadow
- * page and sends KVM back to square one.
- */
- bool write_fault_to_shadow_pgtable;
-
/* set at EPT violation at this point */
unsigned long exit_qualification;
@@ -1907,6 +1890,25 @@ u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu);
* EMULTYPE_COMPLETE_USER_EXIT - Set when the emulator should update interruptibility
* state and inject single-step #DBs after skipping
* an instruction (after completing userspace I/O).
+ *
+ * EMULTYPE_WRITE_PF_TO_SP - Set when emulating an intercepted page fault that
+ * is attempting to write a gfn that contains one or
+ * more of the PTEs used to translate the write itself,
+ * and the owning page table is being shadowed by KVM.
+ * If emulation of the faulting instruction fails and
+ * this flag is set, KVM will exit to userspace instead
+ * of retrying emulation as KVM cannot make forward
+ * progress.
+ *
+ * If emulation fails for a write to guest page tables,
+ * KVM unprotects (zaps) the shadow page for the target
+ * gfn and resumes the guest to retry the non-emulatable
+ * instruction (on hardware). Unprotecting the gfn
+ * doesn't allow forward progress for a self-changing
+ * access because doing so also zaps the translation for
+ * the gfn, i.e. retrying the instruction will hit a
+ * !PRESENT fault, which results in a new shadow page
+ * and sends KVM back to square one.
*/
#define EMULTYPE_NO_DECODE (1 << 0)
#define EMULTYPE_TRAP_UD (1 << 1)
@@ -1916,6 +1918,7 @@ u64 vcpu_tsc_khz(struct kvm_vcpu *vcpu);
#define EMULTYPE_VMWARE_GP (1 << 5)
#define EMULTYPE_PF (1 << 6)
#define EMULTYPE_COMPLETE_USER_EXIT (1 << 7)
+#define EMULTYPE_WRITE_PF_TO_SP (1 << 8)
int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index c8ebe542c565..144c5a01cd77 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -4203,7 +4203,7 @@ void kvm_arch_async_page_ready(struct kvm_vcpu *vcpu, struct kvm_async_pf *work)
work->arch.cr3 != vcpu->arch.mmu->get_guest_pgd(vcpu))
return;
- kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true);
+ kvm_mmu_do_page_fault(vcpu, work->cr2_or_gpa, 0, true, NULL);
}
static int __kvm_faultin_pfn(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
@@ -5664,7 +5664,8 @@ int noinline kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 err
if (r == RET_PF_INVALID) {
r = kvm_mmu_do_page_fault(vcpu, cr2_or_gpa,
- lower_32_bits(error_code), false);
+ lower_32_bits(error_code), false,
+ &emulation_type);
if (KVM_BUG_ON(r == RET_PF_INVALID, vcpu->kvm))
return -EIO;
}
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index cc58631e2336..2cbb155c686c 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -240,6 +240,13 @@ struct kvm_page_fault {
kvm_pfn_t pfn;
hva_t hva;
bool map_writable;
+
+ /*
+ * Indicates the guest is trying to write a gfn that contains one or
+ * more of the PTEs used to translate the write itself, i.e. the access
+ * is changing its own translation in the guest page tables.
+ */
+ bool write_fault_to_shadow_pgtable;
};
int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault);
@@ -273,7 +280,7 @@ enum {
};
static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
- u32 err, bool prefetch)
+ u32 err, bool prefetch, int *emulation_type)
{
struct kvm_page_fault fault = {
.addr = cr2_or_gpa,
@@ -312,6 +319,9 @@ static inline int kvm_mmu_do_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
else
r = vcpu->arch.mmu->page_fault(vcpu, &fault);
+ if (fault.write_fault_to_shadow_pgtable && emulation_type)
+ *emulation_type |= EMULTYPE_WRITE_PF_TO_SP;
+
/*
* Similar to above, prefetch faults aren't truly spurious, and the
* async #PF path doesn't do emulation. Do count faults that are fixed
diff --git a/arch/x86/kvm/mmu/paging_tmpl.h b/arch/x86/kvm/mmu/paging_tmpl.h
index 57f0b75c80f9..5d2958299b4f 100644
--- a/arch/x86/kvm/mmu/paging_tmpl.h
+++ b/arch/x86/kvm/mmu/paging_tmpl.h
@@ -825,10 +825,8 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault
if (r)
return r;
- vcpu->arch.write_fault_to_shadow_pgtable = false;
-
is_self_change_mapping = FNAME(is_self_change_mapping)(vcpu,
- &walker, fault->user, &vcpu->arch.write_fault_to_shadow_pgtable);
+ &walker, fault->user, &fault->write_fault_to_shadow_pgtable);
if (is_self_change_mapping)
fault->max_level = PG_LEVEL_4K;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7713420abab0..ff7f398a0c6a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8463,7 +8463,6 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
}
static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
- bool write_fault_to_shadow_pgtable,
int emulation_type)
{
gpa_t gpa = cr2_or_gpa;
@@ -8534,7 +8533,7 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
* be fixed by unprotecting shadow page and it should
* be reported to userspace.
*/
- return !write_fault_to_shadow_pgtable;
+ return !(emulation_type & EMULTYPE_WRITE_PF_TO_SP);
}
static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
@@ -8782,20 +8781,12 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
int r;
struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;
bool writeback = true;
- bool write_fault_to_spt;
if (unlikely(!kvm_can_emulate_insn(vcpu, emulation_type, insn, insn_len)))
return 1;
vcpu->arch.l1tf_flush_l1d = true;
- /*
- * Clear write_fault_to_shadow_pgtable here to ensure it is
- * never reused.
- */
- write_fault_to_spt = vcpu->arch.write_fault_to_shadow_pgtable;
- vcpu->arch.write_fault_to_shadow_pgtable = false;
-
if (!(emulation_type & EMULTYPE_NO_DECODE)) {
kvm_clear_exception_queue(vcpu);
@@ -8816,7 +8807,6 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
return 1;
}
if (reexecute_instruction(vcpu, cr2_or_gpa,
- write_fault_to_spt,
emulation_type))
return 1;
@@ -8895,8 +8885,7 @@ restart:
return 1;
if (r == EMULATION_FAILED) {
- if (reexecute_instruction(vcpu, cr2_or_gpa, write_fault_to_spt,
- emulation_type))
+ if (reexecute_instruction(vcpu, cr2_or_gpa, emulation_type))
return 1;
return handle_emulation_failure(vcpu, emulation_type);
generated by cgit v1.2.3 (git 2.39.0) at 2024-09-20 14:16:40 +0300