From: Liran Alon <liran.alon@oracle.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Vitaly Kuznetsov" <vkuznets@redhat.com>,
"Wanpeng Li" <wanpengli@tencent.com>,
"Jim Mattson" <jmattson@google.com>,
"Joerg Roedel" <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RESEND PATCH 06/13] KVM: x86: Move #GP injection for VMware into x86_emulate_instruction()
Date: Fri, 23 Aug 2019 16:30:34 +0300 [thread overview]
Message-ID: <1CD69BFC-3E9D-423C-BC9E-892728C68B83@oracle.com> (raw)
In-Reply-To: <20190823010709.24879-7-sean.j.christopherson@intel.com>
> On 23 Aug 2019, at 4:07, Sean Christopherson <sean.j.christopherson@intel.com> wrote:
>
> Immediately inject a #GP when VMware emulation fails and return
> EMULATE_DONE instead of propagating EMULATE_FAIL up the stack. This
> helps pave the way for removing EMULATE_FAIL altogether.
>
> Rename EMULTYPE_VMWARE to EMULTYPE_VMWARE_GP to help document why a #GP
> is injected on emulation failure.
I would rephrase to say that this rename is in order to document that the x86 emulator is called to handle
VMware #GP interception. In theory, VMware could have also added weird behaviour
to #UD interception as-well. :P
Besides minor comments inline below:
Reviewed-by: Liran Alon <liran.alon@oracle.com>
-Liran
>
> Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> ---
> arch/x86/include/asm/kvm_host.h | 2 +-
> arch/x86/kvm/svm.c | 9 ++-------
> arch/x86/kvm/vmx/vmx.c | 9 ++-------
> arch/x86/kvm/x86.c | 14 +++++++++-----
> 4 files changed, 14 insertions(+), 20 deletions(-)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index dd6bd9ed0839..d1d5b5ca1195 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -1318,7 +1318,7 @@ enum emulation_result {
> #define EMULTYPE_TRAP_UD (1 << 1)
> #define EMULTYPE_SKIP (1 << 2)
> #define EMULTYPE_ALLOW_RETRY (1 << 3)
> -#define EMULTYPE_VMWARE (1 << 5)
> +#define EMULTYPE_VMWARE_GP (1 << 5)
> 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/svm.c b/arch/x86/kvm/svm.c
> index b96a119690f4..97562c2c8b7b 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -2768,7 +2768,6 @@ static int gp_interception(struct vcpu_svm *svm)
> {
> struct kvm_vcpu *vcpu = &svm->vcpu;
> u32 error_code = svm->vmcb->control.exit_info_1;
> - int er;
>
> WARN_ON_ONCE(!enable_vmware_backdoor);
>
> @@ -2776,12 +2775,8 @@ static int gp_interception(struct vcpu_svm *svm)
> kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
> return 1;
> }
> - er = kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE);
> - if (er == EMULATE_USER_EXIT)
> - return 0;
> - else if (er != EMULATE_DONE)
> - kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> - return 1;
> + return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
> + EMULATE_USER_EXIT;
> }
>
> static bool is_erratum_383(void)
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 3ee0dd304bc7..25410c58c758 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -4492,7 +4492,6 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
> u32 intr_info, ex_no, error_code;
> unsigned long cr2, rip, dr6;
> u32 vect_info;
> - enum emulation_result er;
>
> vect_info = vmx->idt_vectoring_info;
> intr_info = vmx->exit_intr_info;
> @@ -4514,12 +4513,8 @@ static int handle_exception_nmi(struct kvm_vcpu *vcpu)
> kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
> return 1;
> }
> - er = kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE);
> - if (er == EMULATE_USER_EXIT)
> - return 0;
> - else if (er != EMULATE_DONE)
> - kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> - return 1;
> + return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP) !=
> + EMULATE_USER_EXIT;
> }
>
> /*
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index e0f0e14d8fac..228ca71d5b01 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6210,8 +6210,10 @@ static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
> ++vcpu->stat.insn_emulation_fail;
> trace_kvm_emulate_insn_failed(vcpu);
>
> - if (emulation_type & EMULTYPE_VMWARE)
> - return EMULATE_FAIL;
> + if (emulation_type & EMULTYPE_VMWARE_GP) {
> + kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
I would add here a comment explaining why you can assume #GP error-code is 0.
i.e. Explain that’s because VMware #GP interception is only related to IN{S}, OUT{S} and RDPMC
instructions which all of them raise #GP with error-code of 0.
> + return EMULATE_DONE;
> + }
>
> kvm_queue_exception(vcpu, UD_VECTOR);
>
> @@ -6543,9 +6545,11 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu,
> }
> }
>
> - if ((emulation_type & EMULTYPE_VMWARE) &&
> - !is_vmware_backdoor_opcode(ctxt))
> - return EMULATE_FAIL;
> + if ((emulation_type & EMULTYPE_VMWARE_GP) &&
> + !is_vmware_backdoor_opcode(ctxt)) {
> + kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
Same here.
> + return EMULATE_DONE;
> + }
>
> if (emulation_type & EMULTYPE_SKIP) {
> kvm_rip_write(vcpu, ctxt->_eip);
> --
> 2.22.0
>
next prev parent reply other threads:[~2019-08-23 13:32 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-23 1:06 [RESEND PATCH 00/13] KVM: x86: Remove emulation_result enums Sean Christopherson
2019-08-23 1:06 ` [RESEND PATCH 01/13] KVM: x86: Relocate MMIO exit stats counting Sean Christopherson
2019-08-23 9:15 ` Vitaly Kuznetsov
2019-08-23 14:37 ` Sean Christopherson
2019-08-23 1:06 ` [RESEND PATCH 02/13] KVM: x86: Clean up handle_emulation_failure() Sean Christopherson
2019-08-23 9:23 ` Vitaly Kuznetsov
2019-08-23 12:58 ` Liran Alon
2019-08-23 1:06 ` [RESEND PATCH 03/13] KVM: x86: Refactor kvm_vcpu_do_singlestep() to remove out param Sean Christopherson
2019-08-23 9:32 ` Vitaly Kuznetsov
2019-08-23 13:05 ` Liran Alon
2019-08-23 1:07 ` [RESEND PATCH 04/13] KVM: x86: Drop EMULTYPE_NO_UD_ON_FAIL as a standalone type Sean Christopherson
2019-08-23 9:34 ` Vitaly Kuznetsov
2019-08-23 13:21 ` Liran Alon
2019-08-23 13:32 ` Liran Alon
2019-08-23 21:55 ` Sean Christopherson
2019-08-23 1:07 ` [RESEND PATCH 05/13] KVM: x86: Don't attempt VMWare emulation on #GP with non-zero error code Sean Christopherson
2019-08-23 11:51 ` Vitaly Kuznetsov
2019-08-23 13:23 ` Liran Alon
2019-08-23 1:07 ` [RESEND PATCH 06/13] KVM: x86: Move #GP injection for VMware into x86_emulate_instruction() Sean Christopherson
2019-08-23 12:27 ` Vitaly Kuznetsov
2019-08-23 13:30 ` Liran Alon [this message]
2019-08-23 1:07 ` [RESEND PATCH 07/13] KVM: x86: Add explicit flag for forced emulation on #UD Sean Christopherson
2019-08-23 13:47 ` Liran Alon
2019-08-23 14:44 ` Sean Christopherson
2019-08-23 15:31 ` Liran Alon
2019-08-23 1:07 ` [RESEND PATCH 08/13] KVM: x86: Move #UD injection for failed emulation into emulation code Sean Christopherson
2019-08-23 13:48 ` Liran Alon
2019-08-27 20:22 ` Sean Christopherson
2019-08-23 1:07 ` [RESEND PATCH 09/13] KVM: x86: Exit to userspace on emulation skip failure Sean Christopherson
2019-08-23 1:07 ` [RESEND PATCH 10/13] KVM: x86: Handle emulation failure directly in kvm_task_switch() Sean Christopherson
2019-08-23 1:07 ` [RESEND PATCH 11/13] KVM: x86: Move triple fault request into RM int injection Sean Christopherson
2019-08-23 1:07 ` [RESEND PATCH 12/13] KVM: VMX: Remove EMULATE_FAIL handling in handle_invalid_guest_state() Sean Christopherson
2019-08-23 1:07 ` [RESEND PATCH 13/13] KVM: x86: Remove emulation_result enums, EMULATE_{DONE,FAIL,USER_EXIT} Sean Christopherson
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