diff mbox series

KVM: SVM: Mark SEV launch secret pages as dirty.

Message ID 20200925020011.1159247-1-cfir@google.com
State New
Headers show
Series KVM: SVM: Mark SEV launch secret pages as dirty. | expand

Commit Message

Cfir Cohen Sept. 25, 2020, 2 a.m. UTC 
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().

Fixes: 9c5e0afaf157 ("KVM: SVM: Add support for SEV LAUNCH_SECRET command")
Signed-off-by: Cfir Cohen <cfir@google.com>
---
Changelog since v2:
 - Added 'Fixes' tag, updated comments.
Changelog since v1:
 - Updated commit message.

 arch/x86/kvm/svm/sev.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

Comments

gregkh@linuxfoundation.org Sept. 25, 2020, 4:54 a.m. UTC | #1 
On Thu, Sep 24, 2020 at 07:00:11PM -0700, 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().

> 

> Fixes: 9c5e0afaf157 ("KVM: SVM: Add support for SEV LAUNCH_SECRET command")

> Signed-off-by: Cfir Cohen <cfir@google.com>

> ---

> Changelog since v2:

>  - Added 'Fixes' tag, updated comments.

> Changelog since v1:

>  - Updated commit message.

> 

>  arch/x86/kvm/svm/sev.c | 26 +++++++++++++++++---------

>  1 file changed, 17 insertions(+), 9 deletions(-)

> 


<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree.  Please read:
    https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.

</formletter>
diff mbox series

Patch

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 5573a97f1520..55edaf3577a0 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -440,10 +440,8 @@  static int sev_launch_update_data(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	}
 
 	/*
-	 * The LAUNCH_UPDATE 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.
+	 * Flush (on non-coherent CPUs) before LAUNCH_UPDATE encrypts pages in
+	 * place, the cache may contain data that was written unencrypted.
 	 */
 	sev_clflush_pages(inpages, npages);
 
@@ -799,10 +797,9 @@  static int sev_dbg_crypt(struct kvm *kvm, struct kvm_sev_cmd *argp, bool dec)
 		}
 
 		/*
-		 * The DBG_{DE,EN}CRYPT commands will perform {dec,en}cryption 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.
+		 * Flush (on non-coherent CPUs) before DBG_{DE,EN}CRYPT reads or modifies
+		 * the pages, flush the destination too in case the cache contains its
+		 * current data.
 		 */
 		sev_clflush_pages(src_p, 1);
 		sev_clflush_pages(dst_p, 1);
@@ -850,7 +847,7 @@  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 +860,12 @@  static int sev_launch_secret(struct kvm *kvm, struct kvm_sev_cmd *argp)
 	if (!pages)
 		return -ENOMEM;
 
+	/*
+	 * Flush (on non-coherent CPUs) before LAUNCH_SECRET encrypts pages in
+	 * place, the cache may contain data that was written unencrypted.
+	 */
+	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 +911,11 @@  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;
 }