From: Tom Lendacky <thomas.lendacky@xxxxxxx>
[ 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@xxxxxxxxx>
Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
Message-Id: <b2f9b79d15166f2c3e4375c0d9bc3268b7696455.1620332081.git.thomas.lendacky@xxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 */
--
2.30.2
