kernel/linux.git/arch/x86/kvm, branch v7.1

KVM: SEV: Unmap and unpin the GHCB as needed on vCPU free

2026-06-03T14:43:56+00:00

Unmap and unpin the GHCB as needed when freeing a vCPU. If the VM is destroyed after mapping+pinning the GHCB on #VMGEXIT, without re-running the vCPU, KVM will effectively leak the GHCB and any mappings created for the GHCB. Fixes: 291bd20d5d88 ("KVM: SVM: Add initial support for a VMGEXIT VMEXIT") Cc: stable@vger.kernel.org Tested-by: Michael Roth Reviewed-by: Tom Lendacky Reviewed-by: Michael Roth Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-18-seanjc@google.com> Signed-off-by: Paolo Bonzini Message-ID: <20260529183549.1104619-18-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini

KVM: SEV: Decouple the need to sync the GHCB SA from the need to free the SA

2026-06-03T14:43:56+00:00

Decouple synchronizing the GHCB SA from freeing/unpinning the SA, so that the free/unpin path can be reused when freeing a vCPU. Opportunistically add a WARN to harden KVM against stomping over (and thus leaking) an already-allocated scratch area. Cc: stable@vger.kernel.org Reviewed-by: Tom Lendacky Reviewed-by: Michael Roth Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-17-seanjc@google.com> Signed-off-by: Paolo Bonzini Message-ID: <20260529183549.1104619-17-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini

KVM: SEV: Move sev_free_vcpu() down below sev_es_unmap_ghcb()

2026-06-03T14:43:56+00:00

Relocate sev_free_vcpu() down in sev.c so that it's definition comes after sev_es_unmap_ghcb(). This will allow sharing unmap functionality between the two functions without needing a forward declaration (or weird placement of the common code). No functional change intended. Cc: stable@vger.kernel.org Reviewed-by: Tom Lendacky Reviewed-by: Michael Roth Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-16-seanjc@google.com> Signed-off-by: Paolo Bonzini Message-ID: <20260529183549.1104619-16-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini

KVM: SEV: Read start/end indices of PSC requests exactly once per #VMGEXIT

2026-06-03T14:43:55+00:00

Rework Page State Change (PSC) handling to read the guest-provided start and end indices exactly once, at the beginning of the request. Re-reading the indices is "fine", _if_ the guest is well-behaved. KVM _should_ be safe against concurrent guest modification of the indices, but there is zero reason to introduce unnecessary risk. Reviewed-by: Tom Lendacky Reviewed-by: Michael Roth Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-14-seanjc@google.com> Signed-off-by: Paolo Bonzini Message-ID: <20260529183549.1104619-14-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini

KVM: SEV: Add an anonymous "psc" struct to track current PSC metadata

2026-06-03T14:43:55+00:00

Add a "psc" struct to vcpu_sev_es_state to avoid having to prefix all of the fields with "psc_". Take advantage of the code churn to opportunistically rename local variables to "guest_psc" to make it more obvious that the buffer is guest data, and more importantly, guest accessible! Opportunistically rename inflight => batch_size as well, because there can really only be one operation in-flight (per-vCPU), i.e. "inflight" _looks_ like a boolean, but in actuality is an integer tracking how many pages are being handled by the current operation. No functional change intended. Reviewed-by: Tom Lendacky Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-13-seanjc@google.com> Signed-off-by: Paolo Bonzini Message-ID: <20260529183549.1104619-13-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini

KVM: SEV: Make it more obvious when KVM is writing back the current PSC index

2026-06-03T14:43:55+00:00

Increment the guest-visible "cur_entry" index outside of the for-loop when processing Page State Change entries, and add a comment to make it more obvious which code is operating on trusted data, and which code is touching guest-accessible data. No functional change intended. Reviewed-by: Tom Lendacky Reviewed-by: Michael Roth Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-12-seanjc@google.com> Signed-off-by: Paolo Bonzini Message-ID: <20260529183549.1104619-12-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini

Merge commit 'kvm-psc-for-7.1' into HEAD

2026-05-29T18:25:59+00:00

KVM: SEV: Use READ_ONCE() when reading entries/indices from PSC buffer

2026-05-29T18:25:29+00:00

Use READ_ONCE() when reading entries/indices from the guest-accessible Page State Change buffer to defend against TOCTOU bugs. Don't bother with READ_ONCE()/WRITE_ONCE() for cases where KVM is writing (and not consuming the result!), as the guest isn't supposed to touch the buffer while it's being processed. I.e. using READ_ONCE() is all about protecting against misbehaving guests. Fixes: 9b54e248d264 ("KVM: SEV: Add support to handle Page State Change VMGEXIT") Cc: stable@vger.kernel.org Reviewed-by: Tom Lendacky Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-11-seanjc@google.com> Signed-off-by: Paolo Bonzini

KVM: SEV: Check PSC request indices against the actual size of the buffer

2026-05-29T18:25:29+00:00

When processing Page State Change (PSC) requests, validate the PSC buffer against the effective size of the scratch area, which could be less than the maximum size if the guest provided a pointer that isn't exactly at the start of the GHCB shared buffer. Fixes: 9b54e248d264 ("KVM: SEV: Add support to handle Page State Change VMGEXIT") Cc: stable@vger.kernel.org Reviewed-by: Tom Lendacky Reviewed-by: Michael Roth Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-10-seanjc@google.com> Signed-off-by: Paolo Bonzini

KVM: SEV: Don't explicitly pass PSC buffer to snp_begin_psc()

2026-05-29T18:25:28+00:00

Stop explicitly passing the PSC buffer to snp_begin_psc(): it *must* be the scratch area. This will allow fixing a variety of bugs without further complicating the code. No functional change intended. Cc: stable@vger.kernel.org Reviewed-by: Tom Lendacky Reviewed-by: Michael Roth Signed-off-by: Sean Christopherson Message-ID: <20260501202250.2115252-9-seanjc@google.com> Signed-off-by: Paolo Bonzini