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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 10/28] x86/fpu/xstate: Define the scope of the initial xstate data
Date: Sun, 23 May 2021 12:32:41 -0700	[thread overview]
Message-ID: <20210523193259.26200-11-chang.seok.bae@intel.com> (raw)
In-Reply-To: <20210523193259.26200-1-chang.seok.bae@intel.com>

init_fpstate is used to record the initial xstate value and covers all the
states. But it is wasteful to cover large states all with trivial initial
data.

Limit init_fpstate by clarifying its size and coverage, which are all but
dynamic user states. The dynamic states are assumed to be large but having
initial data with zeros.

Expand copy_xregs_to_kernel_booting() to receive a mask argument of which
states to save.

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:
* Removed the helper functions. (Borislav Petkov)
* Removed 'no functional change' in the changelog. (Borislav Petkov)
* Updated the code comment.
* Moved out the other initialization changes into the previous patch.

Changes from v2:
* Updated the changelog for clarification.
* Updated the code comments.
---
 arch/x86/include/asm/fpu/internal.h |  3 +--
 arch/x86/kernel/fpu/core.c          | 13 ++++++++++---
 arch/x86/kernel/fpu/xstate.c        | 11 +++++++++--
 3 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 46cb51ef4d17..e4afc1831e29 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -272,9 +272,8 @@ static inline void copy_fxregs_to_kernel(struct fpu *fpu)
  * This function is called only during boot time when x86 caps are not set
  * up and alternative can not be used yet.
  */
-static inline void copy_xregs_to_kernel_booting(struct xregs_state *xstate)
+static inline void copy_xregs_to_kernel_booting(struct xregs_state *xstate, u64 mask)
 {
-	u64 mask = xfeatures_mask_all;
 	u32 lmask = mask;
 	u32 hmask = mask >> 32;
 	int err;
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 918930553290..2584a2922fea 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -21,7 +21,10 @@
 
 /*
  * Represents the initial FPU state. It's mostly (but not completely) zeroes,
- * depending on the FPU hardware format:
+ * depending on the FPU hardware format.
+ *
+ * The dynamic user states are excluded as they are large but having initial
+ * values with zeros.
  */
 union fpregs_state init_fpstate __read_mostly;
 
@@ -213,9 +216,13 @@ void fpstate_init(struct fpu *fpu)
 		mask = fpu->state_mask;
 		size = get_xstate_size(fpu->state_mask);
 	} else {
+		/*
+		 * init_fpstate excludes the dynamic user states as they are
+		 * large but having initial values with zeros.
+		 */
 		state = &init_fpstate;
-		mask = xfeatures_mask_all;
-		size = get_xstate_config(XSTATE_MAX_SIZE);
+		mask = (xfeatures_mask_all & ~xfeatures_mask_user_dynamic);
+		size = get_xstate_config(XSTATE_MIN_SIZE);
 	}
 
 	if (!static_cpu_has(X86_FEATURE_FPU)) {
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 0e3f93b03b3f..773f594bd730 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -552,6 +552,7 @@ static void __init print_xstate_offset_size(void)
 static void __init setup_init_fpu_buf(void)
 {
 	static int on_boot_cpu __initdata = 1;
+	u64 mask;
 
 	WARN_ON_FPU(!on_boot_cpu);
 	on_boot_cpu = 0;
@@ -562,8 +563,14 @@ static void __init setup_init_fpu_buf(void)
 	setup_xstate_features();
 	print_xstate_features();
 
+	/*
+	 * Exclude the dynamic user states as they are large but having
+	 * initial values with zeros.
+	 */
+	mask = xfeatures_mask_all & ~xfeatures_mask_user_dynamic;
+
 	if (boot_cpu_has(X86_FEATURE_XSAVES))
-		fpstate_init_xstate(&init_fpstate.xsave, xfeatures_mask_all);
+		fpstate_init_xstate(&init_fpstate.xsave, mask);
 
 	/*
 	 * Init all the features state with header.xfeatures being 0x0
@@ -574,7 +581,7 @@ static void __init setup_init_fpu_buf(void)
 	 * Dump the init state again. This is to identify the init state
 	 * of any feature which is not represented by all zero's.
 	 */
-	copy_xregs_to_kernel_booting(&init_fpstate.xsave);
+	copy_xregs_to_kernel_booting(&init_fpstate.xsave, mask);
 }
 
 static int xfeature_uncompacted_offset(int xfeature_nr)
-- 
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 ` [PATCH v5 05/28] x86/fpu/xstate: Add a new variable to indicate dynamic user states Chang S. Bae
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 ` Chang S. Bae [this message]
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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