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

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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 <thomas.lendacky@amd.com>
Reviewed-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260501202250.2115252-12-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-ID: <20260529183549.1104619-12-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Sean Christopherson 2026-05-29 20:35:36 +02:00 committed by Paolo Bonzini
parent e43ffb69e0
commit 17d62e0b15
1 changed files with 9 additions and 1 deletions
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10
arch/x86/kvm/svm/sev.c
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@ -3947,7 +3947,7 @@ static int snp_begin_psc(struct vcpu_svm *svm)
}
/* Find the start of the next range which needs processing. */
for (idx = idx_start; idx <= idx_end; idx++, hdr->cur_entry++) {
for (idx = idx_start; idx <= idx_end; idx++) {
entry_start = READ_ONCE(entries[idx]);
gfn = entry_start.gfn;
@ -3974,6 +3974,14 @@ static int snp_begin_psc(struct vcpu_svm *svm)
if (npages)
break;
/*
* Increment the guest-visible index to communicate the current
* entry back to the guest, e.g. in case of failure. No need
* for READ_ONCE() as KVM doesn't consume the field, i.e. a
* misbehaving guest can only break itself.
*/
hdr->cur_entry++;
}
if (idx > idx_end) {