From: Sean Christopherson <seanjc@google.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Sean Christopherson <seanjc@google.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,
Brijesh Singh <brijesh.singh@amd.com>,
Tom Lendacky <thomas.lendacky@amd.com>
Subject: [PATCH 3/3] KVM: SVM: Sync GPRs to the GHCB only after VMGEXIT
Date: Fri, 22 Jan 2021 15:50:49 -0800 [thread overview]
Message-ID: <20210122235049.3107620-4-seanjc@google.com> (raw)
In-Reply-To: <20210122235049.3107620-1-seanjc@google.com>
Sync GPRs to the GHCB on VMRUN only if a sync is needed, i.e. if the
previous exit was a VMGEXIT and the guest is expecting some data back.
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/svm/sev.c | 15 ++++++++++-----
arch/x86/kvm/svm/svm.h | 1 +
2 files changed, 11 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index ac652bc476ae..9bd1e1650eb3 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1418,10 +1418,13 @@ static void sev_es_sync_to_ghcb(struct vcpu_svm *svm)
* Copy their values, even if they may not have been written during the
* VM-Exit. It's the guest's responsibility to not consume random data.
*/
- ghcb_set_rax(ghcb, vcpu->arch.regs[VCPU_REGS_RAX]);
- ghcb_set_rbx(ghcb, vcpu->arch.regs[VCPU_REGS_RBX]);
- ghcb_set_rcx(ghcb, vcpu->arch.regs[VCPU_REGS_RCX]);
- ghcb_set_rdx(ghcb, vcpu->arch.regs[VCPU_REGS_RDX]);
+ if (svm->need_sync_to_ghcb) {
+ ghcb_set_rax(ghcb, vcpu->arch.regs[VCPU_REGS_RAX]);
+ ghcb_set_rbx(ghcb, vcpu->arch.regs[VCPU_REGS_RBX]);
+ ghcb_set_rcx(ghcb, vcpu->arch.regs[VCPU_REGS_RCX]);
+ ghcb_set_rdx(ghcb, vcpu->arch.regs[VCPU_REGS_RDX]);
+ svm->need_sync_to_ghcb = false;
+ }
}
static void sev_es_sync_from_ghcb(struct vcpu_svm *svm)
@@ -1441,8 +1444,10 @@ static void sev_es_sync_from_ghcb(struct vcpu_svm *svm)
* VMMCALL allows the guest to provide extra registers. KVM also
* expects RSI for hypercalls, so include that, too.
*
- * Copy their values to the appropriate location if supplied.
+ * Copy their values to the appropriate location if supplied, and
+ * flag that a sync back to the GHCB is needed on the next VMRUN.
*/
+ svm->need_sync_to_ghcb = true;
memset(vcpu->arch.regs, 0, sizeof(vcpu->arch.regs));
vcpu->arch.regs[VCPU_REGS_RAX] = ghcb_get_rax_if_valid(ghcb);
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 0fe874ae5498..4e2e5f9fbfc2 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -192,6 +192,7 @@ struct vcpu_svm {
u64 ghcb_sa_len;
bool ghcb_sa_sync;
bool ghcb_sa_free;
+ bool need_sync_to_ghcb;
};
struct svm_cpu_data {
--
2.30.0.280.ga3ce27912f-goog
next prev parent reply other threads:[~2021-01-22 23:55 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-22 23:50 [PATCH 0/3] KVM: x86: Revert dirty tracking for GPRs Sean Christopherson
2021-01-22 23:50 ` [PATCH 1/3] KVM: SVM: Unconditionally sync GPRs to GHCB on VMRUN of SEV-ES guest Sean Christopherson
2021-01-25 15:05 ` Tom Lendacky
2021-01-22 23:50 ` [PATCH 2/3] KVM: x86: Revert "KVM: x86: Mark GPRs dirty when written" Sean Christopherson
2021-01-22 23:50 ` Sean Christopherson [this message]
2021-01-23 0:09 ` [PATCH 3/3] KVM: SVM: Sync GPRs to the GHCB only after VMGEXIT Tom Lendacky
2021-01-23 0:29 ` Sean Christopherson
2021-01-25 17:22 ` [PATCH 0/3] KVM: x86: Revert dirty tracking for GPRs Paolo Bonzini
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