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| author | Sean Christopherson <seanjc@google.com> | 2026-03-10 16:48:13 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-04-22 13:30:49 +0200 |
| commit | 4df77742e8b9a6b935bdf46f02fd0aca4d4ee7f5 (patch) | |
| tree | 29706a43d5bb0063d6bb0737170f4472e8bbfda4 | |
| parent | e00ef00eb7f9b2be18516fa3732377ffe3ecaf6d (diff) | |
| download | linux-stable-4df77742e8b9a6b935bdf46f02fd0aca4d4ee7f5.tar.gz linux-stable-4df77742e8b9a6b935bdf46f02fd0aca4d4ee7f5.zip | |
KVM: SEV: Lock all vCPUs when synchronzing VMSAs for SNP launch finish
commit cb923ee6a80f4e604e6242a4702b59251e61a380 upstream.
Lock all vCPUs when synchronizing and encrypting VMSAs for SNP guests, as
allowing userspace to manipulate and/or run a vCPU while its state is being
synchronized would at best corrupt vCPU state, and at worst crash the host
kernel.
Opportunistically assert that vcpu->mutex is held when synchronizing its
VMSA (the SEV-ES path already locks vCPUs).
Fixes: ad27ce155566 ("KVM: SEV: Add KVM_SEV_SNP_LAUNCH_FINISH command")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260310234829.2608037-6-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kvm/svm/sev.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 5d4b4d74704d..4370dde0ea25 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -875,6 +875,8 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm) u8 *d; int i; + lockdep_assert_held(&vcpu->mutex); + if (vcpu->arch.guest_state_protected) return -EINVAL; @@ -2460,6 +2462,10 @@ static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp) if (kvm_is_vcpu_creation_in_progress(kvm)) return -EBUSY; + ret = kvm_lock_all_vcpus(kvm); + if (ret) + return ret; + data.gctx_paddr = __psp_pa(sev->snp_context); data.page_type = SNP_PAGE_TYPE_VMSA; @@ -2469,12 +2475,12 @@ static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp) ret = sev_es_sync_vmsa(svm); if (ret) - return ret; + goto out; /* Transition the VMSA page to a firmware state. */ ret = rmp_make_private(pfn, INITIAL_VMSA_GPA, PG_LEVEL_4K, sev->asid, true); if (ret) - return ret; + goto out; /* Issue the SNP command to encrypt the VMSA */ data.address = __sme_pa(svm->sev_es.vmsa); @@ -2483,7 +2489,7 @@ static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp) if (ret) { snp_page_reclaim(kvm, pfn); - return ret; + goto out; } svm->vcpu.arch.guest_state_protected = true; @@ -2497,7 +2503,9 @@ static int snp_launch_update_vmsa(struct kvm *kvm, struct kvm_sev_cmd *argp) svm_enable_lbrv(vcpu); } - return 0; +out: + kvm_unlock_all_vcpus(kvm); + return ret; } static int snp_launch_finish(struct kvm *kvm, struct kvm_sev_cmd *argp) |