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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, jing2.liu@intel.com,
	ravi.v.shankar@intel.com, linux-kernel@vger.kernel.org,
	chang.seok.bae@intel.com
Subject: [PATCH v5 05/28] x86/fpu/xstate: Add a new variable to indicate dynamic user states
Date: Sun, 23 May 2021 12:32:36 -0700	[thread overview]
Message-ID: <20210523193259.26200-6-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20210523193259.26200-1-chang.seok.bae@intel.com>

The xstate per-task buffer is in preparation to be dynamic for user states.
Introduce a new mask variable to indicate the 'dynamic' user states. The
value is determined at boot-time.

The perf subsystem has a separate buffer to save some state only when
needed, not in every context switch. The states are named as 'dynamic'
supervisor states. Some define and helper are not named with dynamic
supervisor states, so rename them.

No functional change.

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 v3:
* Updated the changelog. (Borislav Petkov)
* Updated the code comment. (Borislav Petkov)

Changes from v2:
* Updated the changelog for clarification.
---
 arch/x86/include/asm/fpu/xstate.h | 12 ++++++-----
 arch/x86/kernel/fpu/xstate.c      | 33 ++++++++++++++++++++-----------
 2 files changed, 28 insertions(+), 17 deletions(-)

diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 24bf8d3f559a..6ce8350672c2 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -56,7 +56,7 @@
  * - Don't set the bit corresponding to the dynamic supervisor feature in
  *   IA32_XSS at run time, since it has been set at boot time.
  */
-#define XFEATURE_MASK_DYNAMIC (XFEATURE_MASK_LBR)
+#define XFEATURE_MASK_SUPERVISOR_DYNAMIC (XFEATURE_MASK_LBR)
 
 /*
  * Unsupported supervisor features. When a supervisor feature in this mask is
@@ -66,7 +66,7 @@
 
 /* All supervisor states including supported and unsupported states. */
 #define XFEATURE_MASK_SUPERVISOR_ALL (XFEATURE_MASK_SUPERVISOR_SUPPORTED | \
-				      XFEATURE_MASK_DYNAMIC | \
+				      XFEATURE_MASK_SUPERVISOR_DYNAMIC | \
 				      XFEATURE_MASK_SUPERVISOR_UNSUPPORTED)
 
 #ifdef CONFIG_X86_64
@@ -87,14 +87,16 @@ static inline u64 xfeatures_mask_user(void)
 	return xfeatures_mask_all & XFEATURE_MASK_USER_SUPPORTED;
 }
 
-static inline u64 xfeatures_mask_dynamic(void)
+static inline u64 xfeatures_mask_supervisor_dynamic(void)
 {
 	if (!boot_cpu_has(X86_FEATURE_ARCH_LBR))
-		return XFEATURE_MASK_DYNAMIC & ~XFEATURE_MASK_LBR;
+		return XFEATURE_MASK_SUPERVISOR_DYNAMIC & ~XFEATURE_MASK_LBR;
 
-	return XFEATURE_MASK_DYNAMIC;
+	return XFEATURE_MASK_SUPERVISOR_DYNAMIC;
 }
 
+extern u64 xfeatures_mask_user_dynamic;
+
 extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
 
 extern void __init update_regset_xstate_info(unsigned int size,
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index b55771eb739f..34755612019c 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -61,6 +61,12 @@ static short xsave_cpuid_features[] __initdata = {
  */
 u64 xfeatures_mask_all __read_mostly;
 
+/*
+ * This represents user xstates, a subset of xfeatures_mask_all, saved in a
+ * dynamic kernel XSAVE buffer.
+ */
+u64 xfeatures_mask_user_dynamic __read_mostly;
+
 static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
 static unsigned int xstate_sizes[XFEATURE_MAX]   = { [ 0 ... XFEATURE_MAX - 1] = -1};
 static unsigned int xstate_comp_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1};
@@ -237,7 +243,7 @@ void fpu__init_cpu_xstate(void)
 	 */
 	if (boot_cpu_has(X86_FEATURE_XSAVES)) {
 		wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() |
-				     xfeatures_mask_dynamic());
+				     xfeatures_mask_supervisor_dynamic());
 	}
 }
 
@@ -615,8 +621,8 @@ static void check_xstate_against_struct(int nr)
  * how large the XSAVE buffer needs to be.  We are recalculating
  * it to be safe.
  *
- * Dynamic XSAVE features allocate their own buffers and are not
- * covered by these checks. Only the size of the buffer for task->fpu
+ * Dynamic supervisor XSAVE features allocate their own buffers and are
+ * not covered by these checks. Only the size of the buffer for task->fpu
  * is checked here.
  */
 static void do_extra_xstate_size_checks(void)
@@ -686,7 +692,7 @@ static unsigned int __init get_xsaves_size(void)
  */
 static unsigned int __init get_xsaves_size_no_dynamic(void)
 {
-	u64 mask = xfeatures_mask_dynamic();
+	u64 mask = xfeatures_mask_supervisor_dynamic();
 	unsigned int size;
 
 	if (!mask)
@@ -773,6 +779,7 @@ static int __init init_xstate_size(void)
 static void fpu__init_disable_system_xstate(void)
 {
 	xfeatures_mask_all = 0;
+	xfeatures_mask_user_dynamic = 0;
 	cr4_clear_bits(X86_CR4_OSXSAVE);
 	setup_clear_cpu_cap(X86_FEATURE_XSAVE);
 }
@@ -839,6 +846,8 @@ void __init fpu__init_system_xstate(void)
 	}
 
 	xfeatures_mask_all &= fpu__get_supported_xfeatures_mask();
+	/* Do not support the dynamically allocated buffer yet. */
+	xfeatures_mask_user_dynamic = 0;
 
 	/* Enable xstate instructions to be able to continue with initialization: */
 	fpu__init_cpu_xstate();
@@ -886,7 +895,7 @@ void fpu__resume_cpu(void)
 	 */
 	if (boot_cpu_has(X86_FEATURE_XSAVES)) {
 		wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()  |
-				     xfeatures_mask_dynamic());
+				     xfeatures_mask_supervisor_dynamic());
 	}
 }
 
@@ -1327,8 +1336,8 @@ void copy_supervisor_to_kernel(struct fpu *fpu)
  * @mask: Represent the dynamic supervisor features saved into the xsave area
  *
  * Only the dynamic supervisor states sets in the mask are saved into the xsave
- * area (See the comment in XFEATURE_MASK_DYNAMIC for the details of dynamic
- * supervisor feature). Besides the dynamic supervisor states, the legacy
+ * area (See the comment in XFEATURE_MASK_SUPERVISOR_DYNAMIC for the details of
+ * dynamic supervisor feature). Besides the dynamic supervisor states, the legacy
  * region and XSAVE header are also saved into the xsave area. The supervisor
  * features in the XFEATURE_MASK_SUPERVISOR_SUPPORTED and
  * XFEATURE_MASK_SUPERVISOR_UNSUPPORTED are not saved.
@@ -1337,7 +1346,7 @@ void copy_supervisor_to_kernel(struct fpu *fpu)
  */
 void copy_dynamic_supervisor_to_kernel(struct xregs_state *xstate, u64 mask)
 {
-	u64 dynamic_mask = xfeatures_mask_dynamic() & mask;
+	u64 dynamic_mask = xfeatures_mask_supervisor_dynamic() & mask;
 	u32 lmask, hmask;
 	int err;
 
@@ -1363,9 +1372,9 @@ void copy_dynamic_supervisor_to_kernel(struct xregs_state *xstate, u64 mask)
  * @mask: Represent the dynamic supervisor features restored from the xsave area
  *
  * Only the dynamic supervisor states sets in the mask are restored from the
- * xsave area (See the comment in XFEATURE_MASK_DYNAMIC for the details of
- * dynamic supervisor feature). Besides the dynamic supervisor states, the
- * legacy region and XSAVE header are also restored from the xsave area. The
+ * xsave area (See the comment in XFEATURE_MASK_SUPERVISOR_DYNAMIC for the
+ * details of dynamic supervisor feature). Besides the dynamic supervisor states,
+ * the legacy region and XSAVE header are also restored from the xsave area. The
  * supervisor features in the XFEATURE_MASK_SUPERVISOR_SUPPORTED and
  * XFEATURE_MASK_SUPERVISOR_UNSUPPORTED are not restored.
  *
@@ -1373,7 +1382,7 @@ void copy_dynamic_supervisor_to_kernel(struct xregs_state *xstate, u64 mask)
  */
 void copy_kernel_to_dynamic_supervisor(struct xregs_state *xstate, u64 mask)
 {
-	u64 dynamic_mask = xfeatures_mask_dynamic() & mask;
+	u64 dynamic_mask = xfeatures_mask_supervisor_dynamic() & mask;
 	u32 lmask, hmask;
 	int err;
 
-- 
2.17.1


  parent reply	other threads:[~2021-05-23 19:38 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-23 19:32 [PATCH v5 00/28] x86: Support Intel Advanced Matrix Extensions Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 01/28] x86/fpu/xstate: Modify the initialization helper to handle both static and dynamic buffers Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 02/28] x86/fpu/xstate: Modify state copy helpers " Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 03/28] x86/fpu/xstate: Modify address finders " Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 04/28] x86/fpu/xstate: Modify the context restore helper " Chang S. Bae
2021-05-23 19:32 ` Chang S. Bae [this message]
2021-05-23 19:32 ` [PATCH v5 06/28] x86/fpu/xstate: Add new variables to indicate dynamic xstate buffer size Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 07/28] x86/fpu/xstate: Calculate and remember dynamic xstate buffer sizes Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 08/28] x86/fpu/xstate: Convert the struct fpu 'state' field to a pointer Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 09/28] x86/fpu/xstate: Introduce helpers to manage the xstate buffer dynamically Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 10/28] x86/fpu/xstate: Define the scope of the initial xstate data Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 11/28] x86/fpu/xstate: Update the xstate save function to support dynamic states Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 12/28] x86/fpu/xstate: Update the xstate buffer address finder " Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 13/28] x86/fpu/xstate: Update the xstate context copy function " Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 14/28] x86/fpu/xstate: Prevent unauthorised use of dynamic user state Chang S. Bae
2021-06-16 16:17   ` Dave Hansen
2021-06-16 16:27   ` Dave Hansen
2021-06-16 18:12     ` Andy Lutomirski
2021-06-16 18:47       ` Bae, Chang Seok
2021-06-16 19:01         ` Dave Hansen
2021-06-16 19:23           ` Bae, Chang Seok
2021-06-16 19:28             ` Dave Hansen
2021-06-16 19:37               ` Bae, Chang Seok
2021-06-28 10:11               ` Liu, Jing2
2021-06-29 17:43           ` Bae, Chang Seok
2021-06-29 17:54             ` Dave Hansen
2021-06-29 18:35               ` Bae, Chang Seok
2021-06-29 18:50                 ` Dave Hansen
2021-06-29 19:13                   ` Bae, Chang Seok
2021-06-29 19:26                     ` Dave Hansen
2021-05-23 19:32 ` [PATCH v5 15/28] x86/arch_prctl: Create ARCH_GET_XSTATE/ARCH_PUT_XSTATE Chang S. Bae
2021-05-24 23:10   ` Len Brown
2021-05-25 17:27     ` Borislav Petkov
2021-05-25 17:33       ` Dave Hansen
2021-05-26  0:38     ` Len Brown
2021-05-27 11:14       ` second, sync-alloc syscall Borislav Petkov
2021-05-27 13:59         ` Len Brown
2021-05-27 19:35           ` Andy Lutomirski
2021-05-25 15:46   ` [PATCH v5 15/28] x86/arch_prctl: Create ARCH_GET_XSTATE/ARCH_PUT_XSTATE Dave Hansen
2021-05-23 19:32 ` [PATCH v5 16/28] x86/fpu/xstate: Support ptracer-induced xstate buffer expansion Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 17/28] x86/fpu/xstate: Adjust the XSAVE feature table to address gaps in state component numbers Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 18/28] x86/fpu/xstate: Disable xstate support if an inconsistent state is detected Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 19/28] x86/cpufeatures/amx: Enumerate Advanced Matrix Extension (AMX) feature bits Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 20/28] x86/fpu/amx: Define AMX state components and have it used for boot-time checks Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 21/28] x86/fpu/amx: Initialize child's AMX state Chang S. Bae
2021-05-24  3:09   ` Andy Lutomirski
2021-05-24 17:37     ` Len Brown
2021-05-24 18:13       ` Andy Lutomirski
2021-05-24 18:21         ` Len Brown
2021-05-25  3:44           ` Andy Lutomirski
2021-05-23 19:32 ` [PATCH v5 22/28] x86/fpu/amx: Enable the AMX feature in 64-bit mode Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 23/28] selftest/x86/amx: Test cases for the AMX state management Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 24/28] x86/fpu/xstate: Use per-task xstate mask for saving xstate in signal frame Chang S. Bae
2021-05-24  3:15   ` Andy Lutomirski
2021-05-24 18:06     ` Len Brown
2021-05-25  4:47       ` Andy Lutomirski
2021-05-25 14:04         ` Len Brown
2021-05-23 19:32 ` [PATCH v5 25/28] x86/fpu/xstate: Skip writing zeros to signal frame for dynamic user states if in INIT-state Chang S. Bae
2021-05-24  3:25   ` Andy Lutomirski
2021-05-24 18:15     ` Len Brown
2021-05-24 18:29       ` Dave Hansen
2021-05-25  4:46       ` Andy Lutomirski
2021-05-23 19:32 ` [PATCH v5 26/28] selftest/x86/amx: Test case for AMX state copy optimization in signal delivery Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 27/28] x86/insn/amx: Add TILERELEASE instruction to the opcode map Chang S. Bae
2021-05-23 19:32 ` [PATCH v5 28/28] x86/fpu/amx: Clear the AMX state when appropriate Chang S. Bae
2021-05-24  3:13   ` Andy Lutomirski
2021-05-24 14:10     ` Dave Hansen
2021-05-24 17:32       ` Len Brown
2021-05-24 17:39         ` Dave Hansen
2021-05-24 18:24           ` Len Brown
2021-05-27 11:56             ` Peter Zijlstra
2021-05-27 14:02               ` Len Brown
2021-05-24 14:06   ` Dave Hansen
2021-05-24 17:34     ` Len Brown
2021-05-24 21:11       ` [PATCH v5-fix " Chang S. Bae

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