kvm.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Cathy Avery <cavery@redhat.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com
Cc: vkuznets@redhat.com, wei.huang2@amd.com, sean.j.christopherson@intel.com
Subject: [PATCH 1/2] KVM: nSVM: Track the physical cpu of the vmcb vmrun through the vmcb
Date: Tue, 12 Jan 2021 11:43:12 -0500	[thread overview]
Message-ID: <20210112164313.4204-2-cavery@redhat.com> (raw)
In-Reply-To: <20210112164313.4204-1-cavery@redhat.com>

This patch moves the physical cpu tracking from the vcpu
to the vmcb in svm_switch_vmcb. If either vmcb01 or vmcb02
change physical cpus from one vmrun to the next the vmcb's
previous cpu is preserved for comparison with the current
cpu and the vmcb is marked dirty if different. This prevents
the processor from using old cached data for a vmcb that may
have been updated on a prior run on a different processor.

It also moves the physical cpu check from svm_vcpu_load
to pre_svm_run as the check only needs to be done at run.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Cathy Avery <cavery@redhat.com>
---
 arch/x86/kvm/svm/svm.c | 28 ++++++++++++++++++++--------
 arch/x86/kvm/svm/svm.h |  1 +
 2 files changed, 21 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 62390fbc9233..5b6998ff7aa1 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1287,6 +1287,11 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 
 void svm_switch_vmcb(struct vcpu_svm *svm, struct kvm_vmcb_info *target_vmcb)
 {
+	/*
+	* Track the old VMCB so the new VMCB will be marked
+	* dirty at its next vmrun.
+	*/
+
 	svm->current_vmcb = target_vmcb;
 	svm->vmcb = target_vmcb->ptr;
 	svm->vmcb_pa = target_vmcb->pa;
@@ -1299,11 +1304,12 @@ void svm_switch_vmcb(struct vcpu_svm *svm, struct kvm_vmcb_info *target_vmcb)
 	svm->asid_generation = 0;
 
 	/*
-	* Workaround: we don't yet track the physical CPU that
-	* target_vmcb has run on.
+	* Track the physical CPU the target_vmcb is running on
+	* in order to mark the VMCB dirty if the cpu changes at
+	* its next vmrun.
 	*/
 
-	vmcb_mark_all_dirty(svm->vmcb);
+	svm->current_vmcb->cpu = svm->vcpu.cpu;
 }
 
 static int svm_create_vcpu(struct kvm_vcpu *vcpu)
@@ -1386,11 +1392,6 @@ static void svm_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	struct svm_cpu_data *sd = per_cpu(svm_data, cpu);
 	int i;
 
-	if (unlikely(cpu != vcpu->cpu)) {
-		svm->asid_generation = 0;
-		vmcb_mark_all_dirty(svm->vmcb);
-	}
-
 #ifdef CONFIG_X86_64
 	rdmsrl(MSR_GS_BASE, to_svm(vcpu)->host.gs_base);
 #endif
@@ -3176,6 +3177,17 @@ static void pre_svm_run(struct vcpu_svm *svm)
 {
 	struct svm_cpu_data *sd = per_cpu(svm_data, svm->vcpu.cpu);
 
+	/*
+	* If the previous vmrun of the vmcb occurred on
+	* a different physical cpu then we must mark the vmcb dirty.
+	*/
+
+        if (unlikely(svm->current_vmcb->cpu != svm->vcpu.cpu)) {
+		svm->asid_generation = 0;
+		vmcb_mark_all_dirty(svm->vmcb);
+		svm->current_vmcb->cpu = svm->vcpu.cpu;
+        }
+
 	if (sev_guest(svm->vcpu.kvm))
 		return pre_sev_run(svm, svm->vcpu.cpu);
 
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h
index 86bf443d4b2a..05baee934d03 100644
--- a/arch/x86/kvm/svm/svm.h
+++ b/arch/x86/kvm/svm/svm.h
@@ -85,6 +85,7 @@ struct kvm_vcpu;
 struct kvm_vmcb_info {
 	struct vmcb *ptr;
 	unsigned long pa;
+	int cpu;
 };
 
 struct svm_nested_state {
-- 
2.20.1


  reply	other threads:[~2021-01-12 16:45 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-12 16:43 [PATCH 0/2] KVM: SVM: Track physical cpu and asid_generation via " Cathy Avery
2021-01-12 16:43 ` Cathy Avery [this message]
2021-01-13 12:09   ` [PATCH 1/2] KVM: nSVM: Track the physical cpu of the vmcb vmrun through " Paolo Bonzini
2021-01-12 16:43 ` [PATCH 2/2] KVM: nSVM: Track the ASID generation " Cathy Avery

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210112164313.4204-2-cavery@redhat.com \
    --to=cavery@redhat.com \
    --cc=kvm@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=pbonzini@redhat.com \
    --cc=sean.j.christopherson@intel.com \
    --cc=vkuznets@redhat.com \
    --cc=wei.huang2@amd.com \
    --subject='Re: [PATCH 1/2] KVM: nSVM: Track the physical cpu of the vmcb vmrun through the vmcb' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).