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From: Yu-cheng Yu <yu-cheng.yu@intel.com>
To: linux-kernel@vger.kernel.org, x86@kernel.org,
	"H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Tony Luck <tony.luck@intel.com>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Rik van Riel <riel@surriel.com>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Fenghua Yu <fenghua.yu@intel.com>,
	Peter Zijlstra <peterz@infradead.org>
Cc: Yu-cheng Yu <yu-cheng.yu@intel.com>
Subject: [PATCH 3/3] x86/fpu/xstate: WARN_ONCE on checking alignment of disabled xfeatures
Date: Thu,  9 Jan 2020 13:14:52 -0800	[thread overview]
Message-ID: <20200109211452.27369-4-yu-cheng.yu@intel.com> (raw)
In-Reply-To: <20200109211452.27369-1-yu-cheng.yu@intel.com>

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 <yu-cheng.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@linux.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 73314e8fce02..4fa494073289 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -330,6 +330,13 @@ 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
-- 
2.21.0


  parent reply	other threads:[~2020-01-09 21:17 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-09 21:14 [PATCH 0/3] Fix two issues in XSAVES offset calculation Yu-cheng Yu
2020-01-09 21:14 ` [PATCH 1/3] x86/fpu/xstate: Fix last_good_offset in setup_xstate_features() Yu-cheng Yu
2020-02-11 18:56   ` Borislav Petkov
2020-02-12 14:50   ` [tip: x86/fpu] " tip-bot2 for Yu-cheng Yu
2020-01-09 21:14 ` [PATCH 2/3] x86/fpu/xstate: Fix XSAVES offsets in setup_xstate_comp() Yu-cheng Yu
2020-02-12 14:50   ` [tip: x86/fpu] " tip-bot2 for Yu-cheng Yu
2020-01-09 21:14 ` Yu-cheng Yu [this message]
2020-02-12 14:50   ` [tip: x86/fpu] x86/fpu/xstate: Warn when checking alignment of disabled xfeatures tip-bot2 for Yu-cheng Yu

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