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| author | Keir Fraser <keir@xen.org> | 2010-11-30 11:38:16 +0000 |
|---|---|---|
| committer | Keir Fraser <keir@xen.org> | 2010-11-30 11:38:16 +0000 |
| commit | 8d4f58459ccd828a0dc58a47bb95503fd9381836 (patch) | |
| tree | 0e960aa2851d613533994dfc54da5c786a0d42bb | |
| parent | 5cd5950df7aa96a48aa7f7125c4a69480f862eeb (diff) | |
| download | xen-8d4f58459ccd828a0dc58a47bb95503fd9381836.tar.gz xen-8d4f58459ccd828a0dc58a47bb95503fd9381836.tar.bz2 xen-8d4f58459ccd828a0dc58a47bb95503fd9381836.zip | |
x86 hvm: Do not overwrite boot-cpu capability data on VMX/SVM startup.
Apparently required back in the earliest days of Xen, we now properly
initialise CPU capabilities early during bootstrap. Re-writing
capability data later now causes problems if specific features have
been deliberately masked out.
Thanks to Weidong Han at Intel for finding such a bug where XSAVE
feature is masked out by default, but then erroneously written back
during VMX initialisation. This would cause memory corruption problems
during boot for XSAVE-capable systems.
Signed-off-by: Keir Fraser <keir@xen.org>
xen-unstable changeset: 22451:8420b82c22c2
xen-unstable date: Tue Nov 30 11:34:08 2010 +0000
| -rw-r--r-- | xen/arch/x86/hvm/svm/svm.c | 3 | ||||
| -rw-r--r-- | xen/arch/x86/hvm/vmx/vmx.c | 3 |
2 files changed, 0 insertions, 6 deletions
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c index f262cca5aa..a77639f064 100644 --- a/xen/arch/x86/hvm/svm/svm.c +++ b/xen/arch/x86/hvm/svm/svm.c @@ -889,9 +889,6 @@ void start_svm(struct cpuinfo_x86 *c) return; } - /* Xen does not fill x86_capability words except 0. */ - boot_cpu_data.x86_capability[5] = cpuid_ecx(0x80000001); - if ( !test_bit(X86_FEATURE_SVME, &boot_cpu_data.x86_capability) ) return; diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 98b95d4b46..30ed7b2fc1 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -1433,9 +1433,6 @@ void start_vmx(void) return; } - /* Xen does not fill x86_capability words except 0. */ - boot_cpu_data.x86_capability[4] = cpuid_ecx(1); - if ( !test_bit(X86_FEATURE_VMXE, &boot_cpu_data.x86_capability) ) return; |