diff options
authorPeter Gonda <pgonda@google.com>2021-01-27 08:15:24 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2021-02-13 13:52:56 +0100
commit848bcb0a1d96f67d075465667d3a1ad4af56311e (patch)
parent78e2f71b89b22222583f74803d14f3d90cdf9d12 (diff)
Fix unsynchronized access to sev members through svm_register_enc_region
commit 19a23da53932bc8011220bd8c410cb76012de004 upstream. Grab kvm->lock before pinning memory when registering an encrypted region; sev_pin_memory() relies on kvm->lock being held to ensure correctness when checking and updating the number of pinned pages. Add a lockdep assertion to help prevent future regressions. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Joerg Roedel <joro@8bytes.org> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Brijesh Singh <brijesh.singh@amd.com> Cc: Sean Christopherson <seanjc@google.com> Cc: x86@kernel.org Cc: kvm@vger.kernel.org Cc: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org Fixes: 1e80fdc09d12 ("KVM: SVM: Pin guest memory when SEV is active") Signed-off-by: Peter Gonda <pgonda@google.com> V2 - Fix up patch description - Correct file paths svm.c -> sev.c - Add unlock of kvm->lock on sev_pin_memory error V1 - https://lore.kernel.org/kvm/20210126185431.1824530-1-pgonda@google.com/ Message-Id: <20210127161524.2832400-1-pgonda@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 11 insertions, 7 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 4906e480b5bb..296b0d7570d0 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1835,6 +1835,8 @@ static struct page **sev_pin_memory(struct kvm *kvm, unsigned long uaddr,
struct page **pages;
unsigned long first, last;
+ lockdep_assert_held(&kvm->lock);
if (ulen == 0 || uaddr + ulen < uaddr)
return NULL;
@@ -7091,12 +7093,21 @@ static int svm_register_enc_region(struct kvm *kvm,
if (!region)
return -ENOMEM;
+ mutex_lock(&kvm->lock);
region->pages = sev_pin_memory(kvm, range->addr, range->size, &region->npages, 1);
if (!region->pages) {
ret = -ENOMEM;
+ mutex_unlock(&kvm->lock);
goto e_free;
+ region->uaddr = range->addr;
+ region->size = range->size;
+ mutex_lock(&kvm->lock);
+ list_add_tail(&region->list, &sev->regions_list);
+ mutex_unlock(&kvm->lock);
* The guest may change the memory encryption attribute from C=0 -> C=1
* or vice versa for this memory range. Lets make sure caches are
@@ -7105,13 +7116,6 @@ static int svm_register_enc_region(struct kvm *kvm,
sev_clflush_pages(region->pages, region->npages);
- region->uaddr = range->addr;
- region->size = range->size;
- mutex_lock(&kvm->lock);
- list_add_tail(&region->list, &sev->regions_list);
- mutex_unlock(&kvm->lock);
return ret;