Commit 2f34d421 authored by Sean Christopherson's avatar Sean Christopherson
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KVM: SEV: Document that checking for SEV+ guests when reclaiming memory is "safe" 

Document that the check for an SEV+ guest when reclaiming guest memory is
safe even though kvm->lock isn't held.  This will allow asserting that
kvm->lock is held in the SEV accessors, without triggering false positives
on the "safe" cases.

No functional change intended.

Link: https://patch.msgid.link/20260310234829.2608037-15-seanjc@google.com


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 85d2243a

arch/x86/kvm/svm/sev.c

+7 −1
Original line number Diff line number Diff line
@@ -3293,8 +3293,14 @@ void sev_guest_memory_reclaimed(struct kvm *kvm) 
	 * With SNP+gmem, private/encrypted memory is unreachable via the

	 * hva-based mmu notifiers, i.e. these events are explicitly scoped to

	 * shared pages, where there's no need to flush caches.

	 *

	 * Checking for SEV+ outside of kvm->lock is safe as __sev_guest_init()

	 * can only be done before vCPUs are created, caches can be incoherent

	 * if and only if a vCPU was run, and either this task will see the VM

	 * as being SEV+ or the vCPU won't be to access the memory (because of

	 * the in-progress invalidation).

	 */

	if (!sev_guest(kvm) || sev_snp_guest(kvm))

	if (!____sev_guest(kvm) || ____sev_snp_guest(kvm))

		return;



	sev_writeback_caches(kvm);