From: Joerg Roedel <[email protected]> Take a dedicated KVM SRCU read lock around the guest-owned VMSA memslot and guest_memfd lookup. This makes the reload path self-contained and prevents it from racing a userspace memslot replacement.
Keep the lock through VMCB installation, and release it on all lookup failure paths. Assisted-by: LLM Signed-off-by: Joerg Roedel <[email protected]> --- arch/x86/kvm/svm/sev.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index c16eca9983f3..ee1bf9b4cc53 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -4037,6 +4037,7 @@ static void __sev_snp_reload_vmsa(struct kvm_vcpu *vcpu, gpa_t gpa) unsigned long mmu_seq; struct page *page; kvm_pfn_t pfn; + int idx; lockdep_assert_held(&svm->sev_es.snp_vmsa_mutex); @@ -4068,9 +4069,10 @@ static void __sev_snp_reload_vmsa(struct kvm_vcpu *vcpu, gpa_t gpa) if (!VALID_PAGE(gpa)) return; - slot = gfn_to_memslot(vcpu->kvm, gfn); + idx = srcu_read_lock(&kvm->srcu); + slot = gfn_to_memslot(kvm, gfn); if (!slot) - return; + goto out_unlock; mmu_seq = kvm->mmu_invalidate_seq; smp_rmb(); @@ -4079,8 +4081,8 @@ static void __sev_snp_reload_vmsa(struct kvm_vcpu *vcpu, gpa_t gpa) * The new VMSA will be private memory guest memory, so retrieve the * PFN from the gmem backend. */ - if (kvm_gmem_get_pfn(vcpu->kvm, slot, gfn, &pfn, &page, NULL)) - return; + if (kvm_gmem_get_pfn(kvm, slot, gfn, &pfn, &page, NULL)) + goto out_unlock; read_lock(&kvm->mmu_lock); /* @@ -4097,6 +4099,8 @@ static void __sev_snp_reload_vmsa(struct kvm_vcpu *vcpu, gpa_t gpa) read_unlock(&kvm->mmu_lock); kvm_release_page_clean(page); +out_unlock: + srcu_read_unlock(&kvm->srcu, idx); } /* -- 2.53.0
