From 03974abbf2a1dc99d00cadbeb1664c7711e3909a Mon Sep 17 00:00:00 2001 From: Juergen Gross Date: Thu, 9 Feb 2023 08:22:17 +0100 Subject: [PATCH] x86/mtrr: Revert 90b926e68f50 ("x86/pat: Fix pat_x_mtrr_type() for MTRR disabled case") commit f9f57da2c2d119dbf109e3f6e1ceab7659294046 upstream. Commit 90b926e68f50 ("x86/pat: Fix pat_x_mtrr_type() for MTRR disabled case") broke the use case of running Xen dom0 kernels on machines with an external disk enclosure attached via USB, see Link tag. What this commit was originally fixing - SEV-SNP guests on Hyper-V - is a more specialized situation which has other issues at the moment anyway so reverting this now and addressing the issue properly later is the prudent thing to do. So revert it in time for the 6.2 proper release. [ bp: Rewrite commit message. ] Reported-by: Christian Kujau Tested-by: Christian Kujau Signed-off-by: Juergen Gross Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/4fe9541e-4d4c-2b2a-f8c8-2d34a7284930@nerdbynature.de Cc: Jason Andryuk Signed-off-by: Greg Kroah-Hartman --- arch/x86/mm/pat/memtype.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c index 2642bc4c8ec07..66a209f7eb86d 100644 --- a/arch/x86/mm/pat/memtype.c +++ b/arch/x86/mm/pat/memtype.c @@ -434,8 +434,7 @@ static unsigned long pat_x_mtrr_type(u64 start, u64 end, u8 mtrr_type, uniform; mtrr_type = mtrr_type_lookup(start, end, &uniform); - if (mtrr_type != MTRR_TYPE_WRBACK && - mtrr_type != MTRR_TYPE_INVALID) + if (mtrr_type != MTRR_TYPE_WRBACK) return _PAGE_CACHE_MODE_UC_MINUS; return _PAGE_CACHE_MODE_WB; -- 2.50.1