From: Tom Lendacky thomas.lendacky@amd.com
[ Upstream commit ce7ea0cfdc2e9ff31d12da31c3226deddb9644f5 ]
When an SEV-ES guest is running, the GHCB is unmapped as part of the vCPU run support. However, kvm_vcpu_unmap() triggers an RCU dereference warning with CONFIG_PROVE_LOCKING=y because the SRCU lock is released before invoking the vCPU run support.
Move the GHCB unmapping into the prepare_guest_switch callback, which is invoked while still holding the SRCU lock, eliminating the RCU dereference warning.
Fixes: 291bd20d5d88 ("KVM: SVM: Add initial support for a VMGEXIT VMEXIT") Reported-by: Borislav Petkov bp@alien8.de Signed-off-by: Tom Lendacky thomas.lendacky@amd.com Message-Id: b2f9b79d15166f2c3e4375c0d9bc3268b7696455.1620332081.git.thomas.lendacky@amd.com Signed-off-by: Paolo Bonzini pbonzini@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kvm/svm/sev.c | 5 +---- arch/x86/kvm/svm/svm.c | 3 +++ arch/x86/kvm/svm/svm.h | 1 + 3 files changed, 5 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index ba56f677cc09..dbc6214d69de 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -1668,7 +1668,7 @@ static int sev_es_validate_vmgexit(struct vcpu_svm *svm) return -EINVAL; }
-static void pre_sev_es_run(struct vcpu_svm *svm) +void sev_es_unmap_ghcb(struct vcpu_svm *svm) { if (!svm->ghcb) return; @@ -1704,9 +1704,6 @@ void pre_sev_run(struct vcpu_svm *svm, int cpu) struct svm_cpu_data *sd = per_cpu(svm_data, cpu); int asid = sev_get_asid(svm->vcpu.kvm);
- /* Perform any SEV-ES pre-run actions */ - pre_sev_es_run(svm); - /* Assign the asid allocated with this SEV guest */ svm->asid = asid;
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 276d3c728628..5364458cf60b 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1416,6 +1416,9 @@ static void svm_prepare_guest_switch(struct kvm_vcpu *vcpu) struct svm_cpu_data *sd = per_cpu(svm_data, vcpu->cpu); unsigned int i;
+ if (sev_es_guest(vcpu->kvm)) + sev_es_unmap_ghcb(svm); + if (svm->guest_state_loaded) return;
diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 39e071fdab0c..98da0b91f273 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -571,6 +571,7 @@ void sev_es_init_vmcb(struct vcpu_svm *svm); void sev_es_create_vcpu(struct vcpu_svm *svm); void sev_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, u8 vector); void sev_es_prepare_guest_switch(struct vcpu_svm *svm, unsigned int cpu); +void sev_es_unmap_ghcb(struct vcpu_svm *svm);
/* vmenter.S */