KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault

Add a new emulation type flag to explicitly mark emulation related to a
page fault.  Move the propation of the GPA into the emulator from the
page fault handler into x86_emulate_instruction, using EMULTYPE_PF as an
indicator that cr2 is valid.  Similarly, don't propagate cr2 into the
exception.address when it's *not* valid.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 98959e8cd4489877946d091a9bb5ee297790dbe3..ba4cf00fdb42636d135a2a4400dccfaee2a88d78 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1381,8 +1381,9 @@ extern u64 kvm_mce_cap_supported;
  *                decode the instruction length.  For use *only* by
  *                kvm_x86_ops->skip_emulated_instruction() implementations.
  *
- * EMULTYPE_ALLOW_RETRY - Set when the emulator should resume the guest to
- *                       retry native execution under certain conditions.
+ * EMULTYPE_ALLOW_RETRY_PF - Set when the emulator should resume the guest to
+ *                          retry native execution under certain conditions,
+ *                          Can only be set in conjunction with EMULTYPE_PF.
  *
  * EMULTYPE_TRAP_UD_FORCED - Set when emulating an intercepted #UD that was
  *                          triggered by KVM's magic "force emulation" prefix,
@@ -1395,13 +1396,18 @@ extern u64 kvm_mce_cap_supported;
  *                     backdoor emulation, which is opt in via module param.
  *                     VMware backoor emulation handles select instructions
  *                     and reinjects the #GP for all other cases.
+ *
+ * EMULTYPE_PF - Set when emulating MMIO by way of an intercepted #PF, in which
+ *              case the CR2/GPA value pass on the stack is valid.
  */
 #define EMULTYPE_NO_DECODE         (1 << 0)
 #define EMULTYPE_TRAP_UD           (1 << 1)
 #define EMULTYPE_SKIP              (1 << 2)
-#define EMULTYPE_ALLOW_RETRY       (1 << 3)
+#define EMULTYPE_ALLOW_RETRY_PF            (1 << 3)
 #define EMULTYPE_TRAP_UD_FORCED            (1 << 4)
 #define EMULTYPE_VMWARE_GP         (1 << 5)
+#define EMULTYPE_PF                (1 << 6)
+
 int kvm_emulate_instruction(struct kvm_vcpu *vcpu, int emulation_type);
 int kvm_emulate_instruction_from_buffer(struct kvm_vcpu *vcpu,
                                        void *insn, int insn_len);

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 50a78a01aa0f2b0accf7c9aec19aa04c069e513a..a1dbd13abcaf2476762f351c38fdeca0a926b5d1 100644 (file)
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5415,18 +5415,12 @@ EXPORT_SYMBOL_GPL(kvm_mmu_unprotect_page_virt);
 int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
                       void *insn, int insn_len)
 {
-       int r, emulation_type = 0;
+       int r, emulation_type = EMULTYPE_PF;
        bool direct = vcpu->arch.mmu->direct_map;
 
        if (WARN_ON(!VALID_PAGE(vcpu->arch.mmu->root_hpa)))
                return RET_PF_RETRY;
 
-       /* With shadow page tables, fault_address contains a GVA or nGPA.  */
-       if (vcpu->arch.mmu->direct_map) {
-               vcpu->arch.gpa_available = true;
-               vcpu->arch.gpa_val = cr2_or_gpa;
-       }
-
        r = RET_PF_INVALID;
        if (unlikely(error_code & PFERR_RSVD_MASK)) {
                r = handle_mmio_page_fault(vcpu, cr2_or_gpa, direct);
@@ -5470,7 +5464,7 @@ int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
         * for L1 isn't going to magically fix whatever issue cause L2 to fail.
         */
        if (!mmio_info_in_cache(vcpu, cr2_or_gpa, direct) && !is_guest_mode(vcpu))
-               emulation_type = EMULTYPE_ALLOW_RETRY;
+               emulation_type |= EMULTYPE_ALLOW_RETRY_PF;
 emulate:
        /*
         * On AMD platforms, under certain conditions insn_len may be zero on #NPF.

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index de7f3e3f277cec67bb115f6fe3ead8ad858cd890..1ce7bbc075e4515255305a9cba4820929df5c6b6 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6492,10 +6492,11 @@ static bool reexecute_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
        gpa_t gpa = cr2_or_gpa;
        kvm_pfn_t pfn;
 
-       if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
+       if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
                return false;
 
-       if (WARN_ON_ONCE(is_guest_mode(vcpu)))
+       if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
+           WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
                return false;
 
        if (!vcpu->arch.mmu->direct_map) {
@@ -6583,10 +6584,11 @@ static bool retry_instruction(struct x86_emulate_ctxt *ctxt,
         */
        vcpu->arch.last_retry_eip = vcpu->arch.last_retry_addr = 0;
 
-       if (!(emulation_type & EMULTYPE_ALLOW_RETRY))
+       if (!(emulation_type & EMULTYPE_ALLOW_RETRY_PF))
                return false;
 
-       if (WARN_ON_ONCE(is_guest_mode(vcpu)))
+       if (WARN_ON_ONCE(is_guest_mode(vcpu)) ||
+           WARN_ON_ONCE(!(emulation_type & EMULTYPE_PF)))
                return false;
 
        if (x86_page_table_writing_insn(ctxt))
@@ -6839,8 +6841,19 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
        }
 
 restart:
-       /* Save the faulting GPA (cr2) in the address field */
-       ctxt->exception.address = cr2_or_gpa;
+       if (emulation_type & EMULTYPE_PF) {
+               /* Save the faulting GPA (cr2) in the address field */
+               ctxt->exception.address = cr2_or_gpa;
+
+               /* With shadow page tables, cr2 contains a GVA or nGPA. */
+               if (vcpu->arch.mmu->direct_map) {
+                       vcpu->arch.gpa_available = true;
+                       vcpu->arch.gpa_val = cr2_or_gpa;
+               }
+       } else {
+               /* Sanitize the address out of an abundance of paranoia. */
+               ctxt->exception.address = 0;
+       }
 
        r = x86_emulate_insn(ctxt);