diff mbox series

[v4,04/12] x86/hyperv: set MTRR state when running as SEV-SNP Hyper-V guest

Message ID 20230306163425.8324-5-jgross@suse.com
State New
Headers
Series x86/mtrr: fix handling with PAT but without MTRR |

Commit Message

Juergen Gross March 6, 2023, 4:34 p.m. UTC 
  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@suse.com>
---
V2:
- new patch
---
 arch/x86/kernel/cpu/mshyperv.c | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index f36dc2f796c5..0a6cc3cf8919 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -34,6 +34,7 @@ 
 #include <clocksource/hyperv_timer.h>
 #include <asm/numa.h>
 #include <asm/coco.h>
+#include <asm/mtrr.h>
 
 /* Is Linux running as the root partition? */
 bool hv_root_partition;
@@ -408,6 +409,9 @@  static void __init ms_hyperv_init_platform(void)
 #ifdef CONFIG_SWIOTLB
 			swiotlb_unencrypted_base = ms_hyperv.shared_gpa_boundary;
 #endif
+
+			/* Set WB as the default cache mode. */
+			mtrr_overwrite_state(NULL, 0, MTRR_TYPE_WRBACK);
 		}
 		/* Isolation VMs are unenlightened SEV-based VMs, thus this check: */
 		if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) {