This is a note to let you know that I've just added the patch titled
x86/hyperv: Set MTRR state when running as SEV-SNP Hyper-V guest
to the 6.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-hyperv-set-mtrr-state-when-running-as-sev-snp-hy.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cc68b87b85dd8f166deb638fa0c7efc477943bba
Author: Juergen Gross <jgross@xxxxxxxx>
Date: Tue May 2 14:09:19 2023 +0200
x86/hyperv: Set MTRR state when running as SEV-SNP Hyper-V guest
[ Upstream commit c957f1f3c498bcce85c04e92e60afbae1fd10cde ]
In order to avoid mappings using the UC- cache attribute, set the
MTRR state to use WB caching as the default.
This is needed in order to cope with the fact that PAT is enabled,
while MTRRs are not supported by the hypervisor.
Fixes: 90b926e68f50 ("x86/pat: Fix pat_x_mtrr_type() for MTRR disabled case")
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Tested-by: Michael Kelley <mikelley@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230502120931.20719-5-jgross@xxxxxxxx
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/x86/hyperv/ivm.c b/arch/x86/hyperv/ivm.c
index cc92388b7a999..6f7c1b5606ad4 100644
--- a/arch/x86/hyperv/ivm.c
+++ b/arch/x86/hyperv/ivm.c
@@ -17,6 +17,7 @@
#include <asm/mem_encrypt.h>
#include <asm/mshyperv.h>
#include <asm/hypervisor.h>
+#include <asm/mtrr.h>
#ifdef CONFIG_AMD_MEM_ENCRYPT
@@ -372,6 +373,9 @@ void __init hv_vtom_init(void)
x86_platform.guest.enc_cache_flush_required = hv_vtom_cache_flush_required;
x86_platform.guest.enc_tlb_flush_required = hv_vtom_tlb_flush_required;
x86_platform.guest.enc_status_change_finish = hv_vtom_set_host_visibility;
+
+ /* Set WB as the default cache mode. */
+ mtrr_overwrite_state(NULL, 0, MTRR_TYPE_WRBACK);
}
#endif /* CONFIG_AMD_MEM_ENCRYPT */
