In the past, KVM_SEV_SNP_LAUNCH_UPDATE accepted a non-page-aligned
'uaddr' parameter to copy data from, but continuing to support this with
new functionality like in-place conversion and hugepages in the pipeline
has proven to be more trouble than it is worth, since there are no known
users that have been identified who use a non-page-aligned 'uaddr'
parameter.
Rather than locking guest_memfd into continuing to support this, go
ahead and document page-alignment as a requirement and begin enforcing
this in the handling function.
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
Documentation/virt/kvm/x86/amd-memory-encryption.rst | 2 +-
arch/x86/kvm/svm/sev.c | 6 +++++-
2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/Documentation/virt/kvm/x86/amd-memory-encryption.rst b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
index 1ddb6a86ce7f..5a88d0197cb3 100644
--- a/Documentation/virt/kvm/x86/amd-memory-encryption.rst
+++ b/Documentation/virt/kvm/x86/amd-memory-encryption.rst
@@ -523,7 +523,7 @@ Returns: 0 on success, < 0 on error, -EAGAIN if caller should retry
struct kvm_sev_snp_launch_update {
__u64 gfn_start; /* Guest page number to load/encrypt data into. */
- __u64 uaddr; /* Userspace address of data to be loaded/encrypted. */
+ __u64 uaddr; /* 4k-aligned address of data to be loaded/encrypted. */
__u64 len; /* 4k-aligned length in bytes to copy into guest memory.*/
__u8 type; /* The type of the guest pages being initialized. */
__u8 pad0;
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 362c6135401a..90c512ca24a9 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -2366,6 +2366,11 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp)
params.type != KVM_SEV_SNP_PAGE_TYPE_CPUID))
return -EINVAL;
+ src = params.type == KVM_SEV_SNP_PAGE_TYPE_ZERO ? NULL : u64_to_user_ptr(params.uaddr);
+
+ if (!PAGE_ALIGNED(src))
+ return -EINVAL;
+
npages = params.len / PAGE_SIZE;
/*
@@ -2397,7 +2402,6 @@ static int snp_launch_update(struct kvm *kvm, struct kvm_sev_cmd *argp)
sev_populate_args.sev_fd = argp->sev_fd;
sev_populate_args.type = params.type;
- src = params.type == KVM_SEV_SNP_PAGE_TYPE_ZERO ? NULL : u64_to_user_ptr(params.uaddr);
count = kvm_gmem_populate(kvm, params.gfn_start, src, npages,
sev_gmem_post_populate, &sev_populate_args);
--
2.25.1