From e70b100806d63fb79775858ea92e1a716da46186 Mon Sep 17 00:00:00 2001 From: Yu-cheng Yu Date: Thu, 9 Jan 2020 13:14:52 -0800 Subject: [PATCH] x86/fpu/xstate: Warn when checking alignment of disabled xfeatures An XSAVES component's alignment/offset is meaningful only when the feature is enabled. Return zero and WARN_ONCE on checking alignment of disabled features. Signed-off-by: Yu-cheng Yu Signed-off-by: Borislav Petkov Reviewed-by: Dave Hansen Link: https://lkml.kernel.org/r/20200109211452.27369-4-yu-cheng.yu@intel.com --- arch/x86/kernel/fpu/xstate.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index edcaacd583d87..73fe5979629c8 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -325,6 +325,13 @@ static int xfeature_is_aligned(int xfeature_nr) u32 eax, ebx, ecx, edx; CHECK_XFEATURE(xfeature_nr); + + if (!xfeature_enabled(xfeature_nr)) { + WARN_ONCE(1, "Checking alignment of disabled xfeature %d\n", + xfeature_nr); + return 0; + } + cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); /* * The value returned by ECX[1] indicates the alignment -- 2.30.2