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From: "Chang S. Bae" <chang.seok.bae@intel.com>
To: bp@suse.de, luto@kernel.org, tglx@linutronix.de,
	mingo@kernel.org, x86@kernel.org
Cc: len.brown@intel.com, dave.hansen@intel.com,
	thiago.macieira@intel.com, jing2.liu@intel.com,
	ravi.v.shankar@intel.com, linux-kernel@vger.kernel.org,
	chang.seok.bae@intel.com
Subject: [PATCH v7 26/26] x86/fpu/xstate: Add a sanity check for XFD state when saving XSTATE
Date: Sat, 10 Jul 2021 06:03:13 -0700	[thread overview]
Message-ID: <20210710130313.5072-27-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20210710130313.5072-1-chang.seok.bae@intel.com>

Add a DEBUG sanity check that XFD state matches with XINUSE state.

Instead of reading MSR IA32_XFD directly, read a per-cpu value that is
recorded at every MSR write.

Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Signed-off-by: Chang S. Bae <chang.seok.bae@intel.com>
Reviewed-by: Len Brown <len.brown@intel.com>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
---
Changes from v5:
* Added as a new patch. (Dave Hansen)
---
 arch/x86/include/asm/fpu/internal.h | 15 +++++++++++++++
 arch/x86/kernel/fpu/core.c          | 13 +++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index c9f1573f3ff8..1b3062d5f5a0 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -570,10 +570,25 @@ static inline void switch_fpu_prepare(struct fpu *old_fpu, int cpu)
 
 /* The Extended Feature Disable (XFD) helpers: */
 
+#ifdef CONFIG_X86_DEBUG_FPU
+DECLARE_PER_CPU(u64, xfd_shadow);
+static inline u64 xfd_debug_shadow(void)
+{
+	return this_cpu_read(xfd_shadow);
+}
+
+static inline void xfd_write(u64 value)
+{
+	wrmsrl_safe(MSR_IA32_XFD, value);
+	this_cpu_write(xfd_shadow, value);
+}
+#else
+#define xfd_debug_shadow()	0
 static inline void xfd_write(u64 value)
 {
 	wrmsrl_safe(MSR_IA32_XFD, value);
 }
+#endif
 
 static inline u64 xfd_read(void)
 {
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index e8912b5b9369..1b1306488fb6 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -82,6 +82,10 @@ bool irq_fpu_usable(void)
 }
 EXPORT_SYMBOL(irq_fpu_usable);
 
+#ifdef CONFIG_X86_DEBUG_FPU
+DEFINE_PER_CPU(u64, xfd_shadow);
+#endif
+
 /*
  * Save the FPU register state in fpu->state. The register state is
  * preserved.
@@ -99,6 +103,15 @@ EXPORT_SYMBOL(irq_fpu_usable);
 void save_fpregs_to_fpstate(struct fpu *fpu)
 {
 	if (likely(use_xsave())) {
+		/*
+		 * If XFD is armed for an xfeature, XSAVE* will not save
+		 * its state. Verify XFD is clear for all features that
+		 * are in use before XSAVE*.
+		 */
+		if (IS_ENABLED(CONFIG_X86_DEBUG_FPU) && xfd_capable() &&
+		    boot_cpu_has(X86_FEATURE_XGETBV1))
+			WARN_ON_FPU(xgetbv(1) & xfd_debug_shadow());
+
 		os_xsave(&fpu->state->xsave, fpu->state_mask);
 
 		/*
-- 
2.17.1


      parent reply	other threads:[~2021-07-10 13:09 UTC|newest]

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-10 13:02 [PATCH v7 00/26] x86: Support Intel Advanced Matrix Extensions Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 01/26] x86/fpu/xstate: Modify the initialization helper to handle both static and dynamic buffers Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 02/26] x86/fpu/xstate: Modify state copy helpers " Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 03/26] x86/fpu/xstate: Modify address finders " Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 04/26] x86/fpu/xstate: Add a new variable to indicate dynamic user states Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 05/26] x86/fpu/xstate: Add new variables to indicate dynamic XSTATE buffer size Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 06/26] x86/fpu/xstate: Calculate and remember dynamic XSTATE buffer sizes Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 07/26] x86/fpu/xstate: Convert the struct fpu 'state' field to a pointer Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 08/26] x86/fpu/xstate: Introduce helpers to manage the XSTATE buffer dynamically Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 09/26] x86/fpu/xstate: Update the XSTATE save function to support dynamic states Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 10/26] x86/fpu/xstate: Update the XSTATE buffer address finder " Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 11/26] x86/fpu/xstate: Update the XSTATE context copy function " Chang S. Bae
2021-07-10 13:02 ` [PATCH v7 12/26] x86/fpu/xstate: Use feature disable (XFD) to protect dynamic user state Chang S. Bae
2021-07-13 19:13   ` Thiago Macieira
2021-07-17 15:47     ` Bae, Chang Seok
2021-07-10 13:03 ` [PATCH v7 13/26] x86/fpu/xstate: Support ptracer-induced XSTATE buffer expansion Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 14/26] x86/arch_prctl: Create ARCH_SET_XSTATE_ENABLE/ARCH_GET_XSTATE_ENABLE Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 15/26] x86/fpu/xstate: Support both legacy and expanded signal XSTATE size Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 16/26] x86/fpu/xstate: Adjust the XSAVE feature table to address gaps in state component numbers Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 17/26] x86/fpu/xstate: Disable XSTATE support if an inconsistent state is detected Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 18/26] x86/cpufeatures/amx: Enumerate Advanced Matrix Extension (AMX) feature bits Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 19/26] x86/fpu/amx: Define AMX state components and have it used for boot-time checks Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 20/26] x86/fpu/amx: Initialize child's AMX state Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 21/26] x86/fpu/amx: Enable the AMX feature in 64-bit mode Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 22/26] x86/fpu/xstate: Skip writing zeros to signal frame for dynamic user states if in INIT-state Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 23/26] selftest/x86/amx: Test cases for the AMX state management Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 24/26] x86/insn/amx: Add TILERELEASE instruction to the opcode map Chang S. Bae
2021-07-10 13:03 ` [PATCH v7 25/26] intel_idle/amx: Add SPR support with XTILEDATA capability Chang S. Bae
2021-07-16 17:34   ` Rafael J. Wysocki
2021-07-16 17:37     ` Bae, Chang Seok
2021-07-10 13:03 ` Chang S. Bae [this message]

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