KVM: SEV: Pin guest memory for write for RECEIVE_UPDATE_DATA

Require the target guest page to be writable when pinning memory for
RECEIVE_UPDATE_DATA.  Per the SEV API, the PSP writes to guest memory:

  The result is then encrypted with GCTX.VEK and written to the memory
  pointed to by GUEST_PADDR field.

Fixes: 15fb7de1a7f5 ("KVM: SVM: Add KVM_SEV_RECEIVE_UPDATE_DATA command")
Cc: stable@vger.kernel.org
Cc: Peter Gonda <pgonda@google.com>
Cc: Marc Orr <marcorr@google.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210914210951.2994260-2-seanjc@google.com>
Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>
Reviewed-by: Peter Gonda <pgonda@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 4d68a37..002d988 100644 (file)
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -1473,7 +1473,7 @@ static int sev_receive_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
 
        /* Pin guest memory */
        guest_page = sev_pin_memory(kvm, params.guest_uaddr & PAGE_MASK,
-                                   PAGE_SIZE, &n, 0);
+                                   PAGE_SIZE, &n, 1);
        if (IS_ERR(guest_page)) {
                ret = PTR_ERR(guest_page);
                goto e_free_trans;