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Subject[PATCH 2/4] KVM: SVM: Drop vcpu_svm.vmcb_pa
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Remove vmcb_pa from vcpu_svm and simply read current_vmcb->pa directly in
the one path where it is consumed. Unlike svm->vmcb, use of the current
vmcb's address is very limited, as evidenced by the fact that its use
can be trimmed to a single dereference.

Opportunistically add a comment about using vmcb01 for VMLOAD/VMSAVE, at
first glance using vmcb01 instead of vmcb_pa looks wrong.

No functional change intended.

Cc: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/svm/svm.c | 12 +++++++++---
arch/x86/kvm/svm/svm.h | 1 -
2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 89619cc52cf4..f62c56adf7c9 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1310,7 +1310,6 @@ void svm_switch_vmcb(struct vcpu_svm *svm, struct kvm_vmcb_info *target_vmcb)
{
svm->current_vmcb = target_vmcb;
svm->vmcb = target_vmcb->ptr;
- svm->vmcb_pa = target_vmcb->pa;
}

static int svm_create_vcpu(struct kvm_vcpu *vcpu)
@@ -3704,6 +3703,7 @@ static fastpath_t svm_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
{
struct vcpu_svm *svm = to_svm(vcpu);
+ unsigned long vmcb_pa = svm->current_vmcb->pa;

/*
* VMENTER enables interrupts (host state), but the kernel state is
@@ -3726,12 +3726,18 @@ static noinstr void svm_vcpu_enter_exit(struct kvm_vcpu *vcpu)
lockdep_hardirqs_on(CALLER_ADDR0);

if (sev_es_guest(vcpu->kvm)) {
- __svm_sev_es_vcpu_run(svm->vmcb_pa);
+ __svm_sev_es_vcpu_run(vmcb_pa);
} else {
struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu);

+ /*
+ * Use a single vmcb (vmcb01 because it's always valid) for
+ * context switching guest state via VMLOAD/VMSAVE, that way
+ * the state doesn't need to be copied between vmcb01 and
+ * vmcb02 when switching vmcbs for nested virtualization.
+ */
vmload(svm->vmcb01.pa);
- __svm_vcpu_run(svm->vmcb_pa, (unsigned long *)&vcpu->arch.regs);
+ __svm_vcpu_run(vmcb_pa, (unsigned long *)&vcpu->arch.regs);
vmsave(svm->vmcb01.pa);

vmload(__sme_page_pa(sd->save_area));
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 02f8ece8c741..2173fe985104 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -112,7 +112,6 @@ struct svm_nested_state {
struct vcpu_svm {
struct kvm_vcpu vcpu;
struct vmcb *vmcb;
- unsigned long vmcb_pa;
struct kvm_vmcb_info vmcb01;
struct kvm_vmcb_info *current_vmcb;
struct svm_cpu_data *svm_data;
--
2.31.0.208.g409f899ff0-goog
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