linux-kernel - Re: [PATCH 1/3] KVM: x86: move kvm_inject_gp up from kvm_set

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Date:   Tue, 2 Feb 2021 09:19:29 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH 1/3] KVM: x86: move kvm_inject_gp up from kvm_set_xcr to
 callers

On Tue, Feb 02, 2021, Paolo Bonzini wrote:
> Push the injection of #GP up to the callers, so that they can just use
> kvm_complete_insn_gp.

The SVM and VMX code is identical, IMO we should push all the code to x86.c
instead of shuffling it around.

I'd also like to change svm_exit_handlers to take @vcpu instead of @svm so that
SVM can invoke common handlers directly.

If you agree, I'll send a proper series to do the above, plus whatever other
cleanups I find, e.g. INVD, WBINVD, etc...

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index fa7b2df6422b..bf917efde35c 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1530,7 +1530,7 @@ int kvm_get_dr(struct kvm_vcpu *vcpu, int dr, unsigned long *val);
 unsigned long kvm_get_cr8(struct kvm_vcpu *vcpu);
 void kvm_lmsw(struct kvm_vcpu *vcpu, unsigned long msw);
 void kvm_get_cs_db_l_bits(struct kvm_vcpu *vcpu, int *db, int *l);
-int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr);
+int kvm_emulate_xsetbv(struct kvm_vcpu *vcpu);

 int kvm_get_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr);
 int kvm_set_msr_common(struct kvm_vcpu *vcpu, struct msr_data *msr);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 687876211ebe..842a74d88f1b 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -2334,14 +2334,7 @@ static int wbinvd_interception(struct vcpu_svm *svm)

 static int xsetbv_interception(struct vcpu_svm *svm)
 {
-       u64 new_bv = kvm_read_edx_eax(&svm->vcpu);
-       u32 index = kvm_rcx_read(&svm->vcpu);
-
-       if (kvm_set_xcr(&svm->vcpu, index, new_bv) == 0) {
-               return kvm_skip_emulated_instruction(&svm->vcpu);
-       }
-
-       return 1;
+       return kvm_emulate_xsetbv(&svm->vcpu);
 }

 static int rdpru_interception(struct vcpu_svm *svm)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index cf0c397dc3eb..474a169835de 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5218,16 +5218,6 @@ static int handle_wbinvd(struct kvm_vcpu *vcpu)
        return kvm_emulate_wbinvd(vcpu);
 }

-static int handle_xsetbv(struct kvm_vcpu *vcpu)
-{
-       u64 new_bv = kvm_read_edx_eax(vcpu);
-       u32 index = kvm_rcx_read(vcpu);
-
-       if (kvm_set_xcr(vcpu, index, new_bv) == 0)
-               return kvm_skip_emulated_instruction(vcpu);
-       return 1;
-}
-
 static int handle_apic_access(struct kvm_vcpu *vcpu)
 {
        if (likely(fasteoi)) {
@@ -5689,7 +5679,7 @@ static int (*kvm_vmx_exit_handlers[])(struct kvm_vcpu *vcpu) = {
        [EXIT_REASON_APIC_WRITE]              = handle_apic_write,
        [EXIT_REASON_EOI_INDUCED]             = handle_apic_eoi_induced,
        [EXIT_REASON_WBINVD]                  = handle_wbinvd,
-       [EXIT_REASON_XSETBV]                  = handle_xsetbv,
+       [EXIT_REASON_XSETBV]                  = kvm_emulate_xsetbv,
        [EXIT_REASON_TASK_SWITCH]             = handle_task_switch,
        [EXIT_REASON_MCE_DURING_VMENTRY]      = handle_machine_check,
        [EXIT_REASON_GDTR_IDTR]               = handle_desc,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 14fb8a138ec3..ef630f8d8bd2 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -984,16 +984,17 @@ static int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
        return 0;
 }

-int kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
+int kvm_emulate_xsetbv(struct kvm_vcpu *vcpu)
 {
        if (static_call(kvm_x86_get_cpl)(vcpu) != 0 ||
-           __kvm_set_xcr(vcpu, index, xcr)) {
+           __kvm_set_xcr(vcpu, kvm_rcx_read(vcpu), kvm_read_edx_eax(vcpu))) {
                kvm_inject_gp(vcpu, 0);
                return 1;
        }
-       return 0;
+
+       return kvm_skip_emulated_instruction(vcpu);
 }
-EXPORT_SYMBOL_GPL(kvm_set_xcr);
+EXPORT_SYMBOL_GPL(kvm_emulate_xsetbv);

 bool kvm_is_valid_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
 {