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authorJuergen Gross <jgross@suse.com>2015-01-12 06:15:45 +0100
committerThomas Gleixner <tglx@linutronix.de>2015-01-20 14:33:45 +0100
commit9d34cfdf47963905d792ae9c000efa522739abe4 (patch)
treecc408b47f8f71877647dcf4ab6252f64e96fc1fd
parent4a0d3107d6b19125f21172c2b7d95f9c30ecaf6f (diff)
downloadlinux-9d34cfdf47963905d792ae9c000efa522739abe4.tar.gz
x86: Don't rely on VMWare emulating PAT MSR correctly
VMWare seems not to emulate the PAT MSR correctly: reaeding MSR_IA32_CR_PAT returns 0 even after writing another value to it. Commit bd809af16e3ab triggers this VMWare bug when the kernel is booted as a VMWare guest. Detect this bug and don't use the read value if it is 0. Fixes: bd809af16e3ab "x86: Enable PAT to use cache mode translation tables" Reported-and-tested-by: Jongman Heo <jongman.heo@samsung.com> Acked-by: Alok N Kataria <akataria@vmware.com> Signed-off-by: Juergen Gross <jgross@suse.com> Link: http://lkml.kernel.org/r/1421039745-14335-1-git-send-email-jgross@suse.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
-rw-r--r--arch/x86/mm/pat.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/x86/mm/pat.c b/arch/x86/mm/pat.c
index edf299c8ff6..7ac68698406 100644
--- a/arch/x86/mm/pat.c
+++ b/arch/x86/mm/pat.c
@@ -234,8 +234,13 @@ void pat_init(void)
PAT(4, WB) | PAT(5, WC) | PAT(6, UC_MINUS) | PAT(7, UC);
/* Boot CPU check */
- if (!boot_pat_state)
+ if (!boot_pat_state) {
rdmsrl(MSR_IA32_CR_PAT, boot_pat_state);
+ if (!boot_pat_state) {
+ pat_disable("PAT read returns always zero, disabled.");
+ return;
+ }
+ }
wrmsrl(MSR_IA32_CR_PAT, pat);