On 5/7/2025 3:12 PM, Borislav Petkov wrote:
On Tue, May 06, 2025 at 06:35:29PM +0000, Ashish Kalra wrote:
From: Ashish Kalra <ashish.ka...@amd.com>
When the shared pages are being made private during kdump preparation
there are additional checks to handle shared GHCB pages.
These additional checks include handling the case of GHCB page being
contained within a huge page.
The check for handling the case of GHCB contained within a huge
page incorrectly skips a page just below the GHCB page from being
transitioned back to private during kdump preparation.
This skipped page causes a 0x404 #VC exception when it is accessed
later while dumping guest memory during vmcore generation via kdump.
Correct the range to be checked for GHCB contained in a huge page.
Also ensure that the skipped huge page containing the GHCB page is
transitioned back to private by applying the correct address mask
later when changing GHCBs to private at end of kdump preparation.
Fixes: 3074152e56c9 ("x86/sev: Convert shared memory back to private on kexec")
Cc: sta...@vger.kernel.org
Signed-off-by: Ashish Kalra <ashish.ka...@amd.com>
---
arch/x86/coco/sev/core.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
Ok, I've pushed both patches here:
https://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git/log/?h=tip-x86-urgent-sev
Please have those who are affected by the issues test and report back.
Thx.
I tested the failure scenario with the patch hosted in the referenced
Git tree [1]. The patch resolves the issue.
Tested-by: Srikanth Aithal <srait...@amd.com>
[1]:
https://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git/log/?h=tip-x86-urgent-sev
