Messages in this thread | | | Subject | Re: [PATCH v2 1/3] KVM: x86: Add EMULTYPE_PF when emulation is triggered by a page fault | From | Xiaoyao Li <> | Date | Wed, 19 Feb 2020 17:01:41 +0800 |
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On 2/19/2020 7:03 AM, Sean Christopherson wrote: > 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> > --- > arch/x86/include/asm/kvm_host.h | 12 +++++++++--- > arch/x86/kvm/mmu/mmu.c | 10 ++-------- > arch/x86/kvm/x86.c | 25 +++++++++++++++++++------ > 3 files changed, 30 insertions(+), 17 deletions(-) > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 4dffbc10d3f8..10c1e8f472b6 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -1370,8 +1370,9 @@ 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, > @@ -1384,13 +1385,18 @@ 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)
How about naming it as EMULTYPE_PF_ALLOW_RETRY and exchanging the bit position with EMULTYPE_PF ?
> #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 7011a4e54866..258624d46588 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -5416,18 +5416,12 @@ 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); > @@ -5472,7 +5466,7 @@ 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 fbabb2f06273..92af6c5a69e3 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -6483,10 +6483,11 @@ 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) { > @@ -6574,10 +6575,11 @@ 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)) > @@ -6830,8 +6832,19 @@ 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); > >
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