* [PATCH for 4.19] Fix unsynchronized access to sev members through svm_register_enc_region
@ 2021-02-08 16:48 Peter Gonda
2021-02-08 16:53 ` Paolo Bonzini
0 siblings, 1 reply; 2+ messages in thread
From: Peter Gonda @ 2021-02-08 16:48 UTC (permalink / raw)
To: stable
Cc: Peter Gonda, Thomas Gleixner, Ingo Molnar, H. Peter Anvin,
Paolo Bonzini, Joerg Roedel, Tom Lendacky, Brijesh Singh,
Sean Christopherson, x86, kvm, linux-kernel
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>
---
arch/x86/kvm/svm.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 2b506904be02..93c89f1ffc5d 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1830,6 +1830,8 @@ 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;
@@ -7086,12 +7088,21 @@ 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, ®ion->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(®ion->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
@@ -7100,13 +7111,6 @@ 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(®ion->list, &sev->regions_list);
- mutex_unlock(&kvm->lock);
-
return ret;
e_free:
--
2.30.0.478.g8a0d178c01-goog
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH for 4.19] Fix unsynchronized access to sev members through svm_register_enc_region
2021-02-08 16:48 [PATCH for 4.19] Fix unsynchronized access to sev members through svm_register_enc_region Peter Gonda
@ 2021-02-08 16:53 ` Paolo Bonzini
0 siblings, 0 replies; 2+ messages in thread
From: Paolo Bonzini @ 2021-02-08 16:53 UTC (permalink / raw)
To: Peter Gonda, stable
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Joerg Roedel,
Tom Lendacky, Brijesh Singh, Sean Christopherson, x86, kvm,
linux-kernel
On 08/02/21 17:48, Peter Gonda wrote:
> 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>
> ---
> arch/x86/kvm/svm.c | 18 +++++++++++-------
> 1 file changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
> index 2b506904be02..93c89f1ffc5d 100644
> --- a/arch/x86/kvm/svm.c
> +++ b/arch/x86/kvm/svm.c
> @@ -1830,6 +1830,8 @@ 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;
>
> @@ -7086,12 +7088,21 @@ 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, ®ion->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(®ion->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
> @@ -7100,13 +7111,6 @@ 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(®ion->list, &sev->regions_list);
> - mutex_unlock(&kvm->lock);
> -
> return ret;
>
> e_free:
>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
^ permalink raw reply [flat|nested] 2+ messages in thread
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