From f9f57da2c2d119dbf109e3f6e1ceab7659294046 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 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 --- 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 fb4b1b5e0dea..46de9cf5c91d 100644 --- a/arch/x86/mm/pat/memtype.c +++ b/arch/x86/mm/pat/memtype.c @@ -387,8 +387,7 @@ 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;