From: Wei Huang <whuang2@amd.com>
To: Paolo Bonzini <pbonzini@redhat.com>,
Wei Huang <wei.huang2@amd.com>,
kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, vkuznets@redhat.com,
seanjc@google.com, joro@8bytes.org, bp@alien8.de,
tglx@linutronix.de, mingo@redhat.com, x86@kernel.org,
jmattson@google.com, wanpengli@tencent.com, bsd@redhat.com,
dgilbert@redhat.com, mlevitsk@redhat.com
Subject: Re: [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions
Date: Fri, 15 Jan 2021 01:00:22 -0600 [thread overview]
Message-ID: <ed93c796-1750-7cb8-ed4d-dc9c4b68b5a3@amd.com> (raw)
In-Reply-To: <090232a9-7a87-beb9-1402-726bb7cab7e6@redhat.com>
On 1/12/21 8:01 AM, Paolo Bonzini wrote:
> On 12/01/21 07:37, Wei Huang wrote:
>> static int gp_interception(struct vcpu_svm *svm)
>> {
>> struct kvm_vcpu *vcpu = &svm->vcpu;
>> u32 error_code = svm->vmcb->control.exit_info_1;
>> -
>> - WARN_ON_ONCE(!enable_vmware_backdoor);
>> + int rc;
>> /*
>> - * VMware backdoor emulation on #GP interception only handles IN{S},
>> - * OUT{S}, and RDPMC, none of which generate a non-zero error code.
>> + * Only VMware backdoor and SVM VME errata are handled. Neither of
>> + * them has non-zero error codes.
>> */
>> if (error_code) {
>> kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
>> return 1;
>> }
>> - return kvm_emulate_instruction(vcpu, EMULTYPE_VMWARE_GP);
>> +
>> + rc = kvm_emulate_instruction(vcpu, EMULTYPE_PARAVIRT_GP);
>> + if (rc > 1)
>> + rc = svm_emulate_vm_instr(vcpu, rc);
>> + return rc;
>> }
>>
>
> Passing back the third byte is quick hacky. Instead of this change to
> kvm_emulate_instruction, I'd rather check the instruction bytes in
> gp_interception before calling kvm_emulate_instruction. That would be
> something like:
>
> - move "kvm_clear_exception_queue(vcpu);" inside the "if
> (!(emulation_type & EMULTYPE_NO_DECODE))". It doesn't apply when you
> are coming back from userspace.
>
> - extract the "if (!(emulation_type & EMULTYPE_NO_DECODE))" body to a
> new function x86_emulate_decoded_instruction. Call it from
> gp_interception, we know this is not a pagefault and therefore
> vcpu->arch.write_fault_to_shadow_pgtable must be false.
If the whole body inside if-statement is moved out, do you expect the
interface of x86_emulate_decoded_instruction to be something like:
int x86_emulate_decoded_instruction(struct kvm_vcpu *vcpu,
gpa_t cr2_or_gpa,
int emulation_type, void *insn,
int insn_len,
bool write_fault_to_spt)
And if so, what is the emulation type to use when calling this function
from svm.c? EMULTYPE_VMWARE_GP?
>
> - check ctxt->insn_bytes for an SVM instruction
>
> - if not an SVM instruction, call kvm_emulate_instruction(vcpu,
> EMULTYPE_VMWARE_GP|EMULTYPE_NO_DECODE).
>
> Thanks,
>
> Paolo
>
next prev parent reply other threads:[~2021-01-15 7:01 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-12 6:37 [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Wei Huang
2021-01-12 6:37 ` [PATCH 2/2] KVM: SVM: Add support for VMCB address check change Wei Huang
2021-01-12 19:18 ` Sean Christopherson
2021-01-14 11:39 ` Maxim Levitsky
2021-01-14 12:04 ` Maxim Levitsky
2021-01-12 11:09 ` [PATCH 1/2] KVM: x86: Add emulation support for #GP triggered by VM instructions Maxim Levitsky
2021-01-12 21:05 ` Wei Huang
2021-01-12 12:15 ` Vitaly Kuznetsov
2021-01-12 15:11 ` Andy Lutomirski
2021-01-12 15:17 ` Maxim Levitsky
2021-01-12 15:22 ` Andy Lutomirski
2021-01-12 15:46 ` Bandan Das
2021-01-12 15:51 ` Andy Lutomirski
2021-01-12 17:56 ` Sean Christopherson
2021-01-13 4:55 ` Wei Huang
2021-01-12 21:50 ` Wei Huang
2021-01-12 14:01 ` Paolo Bonzini
2021-01-12 17:42 ` Sean Christopherson
2021-01-13 12:35 ` Paolo Bonzini
2021-01-15 7:00 ` Wei Huang [this message]
2021-01-17 18:20 ` Paolo Bonzini
2021-01-12 17:36 ` Sean Christopherson
2021-01-12 17:59 ` Sean Christopherson
2021-01-12 18:58 ` Andy Lutomirski
2021-01-13 5:15 ` Wei Huang
2021-01-14 11:42 ` Maxim Levitsky
2021-01-13 5:03 ` Wei Huang
2021-01-13 12:40 ` Paolo Bonzini
2021-01-12 19:40 ` Sean Christopherson
2021-01-12 20:00 ` Bandan Das
2021-01-14 11:47 ` Maxim Levitsky
2021-01-14 17:19 ` Sean Christopherson
2021-01-14 11:55 ` Maxim Levitsky
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