Re: [PATCH v2] KVM: SVM: Mark SEV launch secret pages as dirty.

Brijesh Singh
2020-08-10T11:05:55Z

On 8/7/20 7:37 PM, Cfir Cohen wrote:
> The LAUNCH_SECRET command performs encryption of the
> launch secret memory contents. Mark pinned pages as
> dirty, before unpinning them.
> This matches the logic in sev_launch_update_data().
>
> Signed-off-by: Cfir Cohen <cfir@google.com>
> ---
> Changelog since v1:
> - Updated commit message.
>
> arch/x86/kvm/svm/sev.c | 15 ++++++++++++++-
> 1 file changed, 14 insertions(+), 1 deletion(-)

Reviewed-by: Brijesh Singh <brijesh.singh@amd.com>

>
> diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
> index 5573a97f1520..37c47d26b9f7 100644
> --- a/arch/x86/kvm/svm/sev.c
> +++ b/arch/x86/kvm/svm/sev.c
> @@ -850,7 +850,7 @@ static int sev_launch_secret(struct kvm *kvm, struct kvm_sev_cmd *argp)
> struct kvm_sev_launch_secret params;
> struct page **pages;
> void *blob, *hdr;
> - unsigned long n;
> + unsigned long n, i;
> int ret, offset;
>
> if (!sev_guest(kvm))
> @@ -863,6 +863,14 @@ static int sev_launch_secret(struct kvm *kvm, struct kvm_sev_cmd *argp)
> if (!pages)
> return -ENOMEM;
>
> + /*
> + * The LAUNCH_SECRET command will perform in-place encryption of the
> + * memory content (i.e it will write the same memory region with C=1).
> + * It's possible that the cache may contain the data with C=0, i.e.,
> + * unencrypted so invalidate it first.
> + */
> + sev_clflush_pages(pages, n);
> +
> /*
> * The secret must be copied into contiguous memory region, lets verify
> * that userspace memory pages are contiguous before we issue command.
> @@ -908,6 +916,11 @@ static int sev_launch_secret(struct kvm *kvm, struct kvm_sev_cmd *argp)
> e_free:
> kfree(data);
> e_unpin_memory:
> + /* content of memory is updated, mark pages dirty */
> + for (i = 0; i < n; i++) {
> + set_page_dirty_lock(pages[i]);
> + mark_page_accessed(pages[i]);
> + }
> sev_unpin_memory(kvm, pages, n);
> return ret;
> }