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,
Reiji Watanabe <reijiw@google.com>
Subject: [PATCH 1/3] KVM: VMX: Drop explicit zeroing of MSR guest values at vCPU creation
Date: Tue, 14 Sep 2021 16:08:38 -0700 [thread overview]
Message-ID: <20210914230840.3030620-2-seanjc@google.com> (raw)
In-Reply-To: <20210914230840.3030620-1-seanjc@google.com>
Don't zero out user return and nested MSRs during vCPU creation, and
instead rely on vcpu_vmx being zero-allocated. Explicitly zeroing MSRs
is not wrong, and is in fact necessary if KVM ever emulates vCPU RESET
outside of vCPU creation, but zeroing only a subset of MSRs is confusing.
Poking directly into KVM's backing is also undesirable in that it doesn't
scale and is error prone. Ideally KVM would have a common RESET path for
all MSRs, e.g. by expanding kvm_set_msr(), which would obviate the need
for this out-of-bad code (to support standalone RESET).
No functional change intended.
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
arch/x86/kvm/vmx/vmx.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fada1055f325..dc274b4c9912 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6818,10 +6818,8 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
goto free_vpid;
}
- for (i = 0; i < kvm_nr_uret_msrs; ++i) {
- vmx->guest_uret_msrs[i].data = 0;
+ for (i = 0; i < kvm_nr_uret_msrs; ++i)
vmx->guest_uret_msrs[i].mask = -1ull;
- }
if (boot_cpu_has(X86_FEATURE_RTM)) {
/*
* TSX_CTRL_CPUID_CLEAR is handled in the CPUID interception.
@@ -6878,8 +6876,6 @@ static int vmx_create_vcpu(struct kvm_vcpu *vcpu)
if (nested)
memcpy(&vmx->nested.msrs, &vmcs_config.nested, sizeof(vmx->nested.msrs));
- else
- memset(&vmx->nested.msrs, 0, sizeof(vmx->nested.msrs));
vcpu_setup_sgx_lepubkeyhash(vcpu);
--
2.33.0.309.g3052b89438-goog
next prev parent reply other threads:[~2021-09-14 23:09 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-14 23:08 [PATCH 0/3] KVM: x86: Clean up RESET "emulation" Sean Christopherson
2021-09-14 23:08 ` Sean Christopherson [this message]
2021-09-14 23:08 ` [PATCH 2/3] KVM: VMX: Move RESET emulation to vmx_vcpu_reset() Sean Christopherson
2021-09-15 10:30 ` Vitaly Kuznetsov
2021-09-15 17:34 ` Sean Christopherson
2021-09-16 7:19 ` Vitaly Kuznetsov
2021-09-16 19:01 ` Sean Christopherson
2021-09-14 23:08 ` [PATCH 3/3] KVM: SVM: Move RESET emulation to svm_vcpu_reset() Sean Christopherson
2021-09-17 16:15 ` [PATCH 0/3] KVM: x86: Clean up RESET "emulation" Paolo Bonzini
2021-09-17 17:34 ` Sean Christopherson
2021-09-17 17:37 ` Paolo Bonzini
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