From: Sean Christopherson <seanjc@google.com>
To: Wei Huang <wei.huang2@amd.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
pbonzini@redhat.com, vkuznets@redhat.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: Tue, 12 Jan 2021 11:40:48 -0800 [thread overview]
Message-ID: <X/37QBMHxH8otaMa@google.com> (raw)
In-Reply-To: <20210112063703.539893-1-wei.huang2@amd.com>
On Tue, Jan 12, 2021, Wei Huang wrote:
> +/* Emulate SVM VM execution instructions */
> +static int svm_emulate_vm_instr(struct kvm_vcpu *vcpu, u8 modrm)
> +{
> + struct vcpu_svm *svm = to_svm(vcpu);
> +
> + switch (modrm) {
> + case 0xd8: /* VMRUN */
> + return vmrun_interception(svm);
> + case 0xda: /* VMLOAD */
> + return vmload_interception(svm);
> + case 0xdb: /* VMSAVE */
> + return vmsave_interception(svm);
> + default:
> + /* inject a #GP for all other cases */
> + kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> + return 1;
> + }
> +}
v> +
> 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;
> }
...
> +static int is_vm_instr_opcode(struct x86_emulate_ctxt *ctxt)
> +{
> + unsigned long rax;
> +
> + if (ctxt->b != 0x1)
> + return 0;
> +
> + switch (ctxt->modrm) {
> + case 0xd8: /* VMRUN */
> + case 0xda: /* VMLOAD */
> + case 0xdb: /* VMSAVE */
> + rax = kvm_register_read(emul_to_vcpu(ctxt), VCPU_REGS_RAX);
> + if (!kvm_is_host_reserved_region(rax))
> + return 0;
> + break;
> + default:
> + return 0;
> + }
> +
> + return ctxt->modrm;
> +}
> +
> static bool is_vmware_backdoor_opcode(struct x86_emulate_ctxt *ctxt)
> {
> switch (ctxt->opcode_len) {
> @@ -7305,6 +7327,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt;
> bool writeback = true;
> bool write_fault_to_spt;
> + int vminstr;
>
> if (unlikely(!kvm_x86_ops.can_emulate_instruction(vcpu, insn, insn_len)))
> return 1;
> @@ -7367,10 +7390,14 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> }
> }
>
> - if ((emulation_type & EMULTYPE_VMWARE_GP) &&
> - !is_vmware_backdoor_opcode(ctxt)) {
> - kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> - return 1;
> + if (emulation_type & EMULTYPE_PARAVIRT_GP) {
> + vminstr = is_vm_instr_opcode(ctxt);
> + if (!vminstr && !is_vmware_backdoor_opcode(ctxt)) {
> + kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> + return 1;
> + }
> + if (vminstr)
> + return vminstr;
I'm pretty sure this doesn't correctly handle a VM-instr in L2 that hits a bad
L0 GPA and that L1 wants to intercept. The intercept bitmap isn't checked until
x86_emulate_insn(), and the vm*_interception() helpers expect nested VM-Exits to
be handled further up the stack.
> }
>
> /*
> --
> 2.27.0
>
next prev parent reply other threads:[~2021-01-12 19:42 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
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 [this message]
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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