From b6f42a4a3c886bd18baf319d433a841ac9942c02 Mon Sep 17 00:00:00 2001 From: Fenghua Yu Date: Thu, 29 May 2014 11:12:31 -0700 Subject: x86/xsaves: Add a kernel parameter noxsaves to disable xsaves/xrstors This patch adds a kernel parameter noxsaves to disable xsaves/xrstors feature. The kernel will fall back to use xsaveopt and xrstor to save and restor xstates. By using this parameter, xsave area occupies more memory because standard form of xsave area in xsaveopt/xrstor occupies more memory than compacted form of xsave area. This patch adds a description of the kernel parameter noxsaveopt in doc. The code to support the parameter noxsaveopt has been in the kernel before. This patch just adds the description of this parameter in the doc. Signed-off-by: Fenghua Yu Link: http://lkml.kernel.org/r/1401387164-43416-4-git-send-email-fenghua.yu@intel.com Signed-off-by: H. Peter Anvin --- arch/x86/kernel/cpu/common.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index e7c4b979d504..cdc95852532d 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -146,6 +146,7 @@ static int __init x86_xsave_setup(char *s) { setup_clear_cpu_cap(X86_FEATURE_XSAVE); setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT); + setup_clear_cpu_cap(X86_FEATURE_XSAVES); setup_clear_cpu_cap(X86_FEATURE_AVX); setup_clear_cpu_cap(X86_FEATURE_AVX2); return 1; @@ -159,6 +160,13 @@ static int __init x86_xsaveopt_setup(char *s) } __setup("noxsaveopt", x86_xsaveopt_setup); +static int __init x86_xsaves_setup(char *s) +{ + setup_clear_cpu_cap(X86_FEATURE_XSAVES); + return 1; +} +__setup("noxsaves", x86_xsaves_setup); + #ifdef CONFIG_X86_32 static int cachesize_override = -1; static int disable_x86_serial_nr = 1; -- cgit v1.2.2 From 21e726c4a3625a1038e97795b7aad97109ba7e19 Mon Sep 17 00:00:00 2001 From: Fenghua Yu Date: Thu, 29 May 2014 11:12:39 -0700 Subject: x86/xsaves: Clear reserved bits in xsave header The reserved bits (128~511) in the xsave header must be zero according to X86 SDM. Clear the bits in this patch. Signed-off-by: Fenghua Yu Link: http://lkml.kernel.org/r/1401387164-43416-12-git-send-email-fenghua.yu@intel.com Signed-off-by: H. Peter Anvin --- arch/x86/kernel/i387.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c index d5dd80814419..a9a4229f6161 100644 --- a/arch/x86/kernel/i387.c +++ b/arch/x86/kernel/i387.c @@ -375,7 +375,7 @@ int xstateregs_set(struct task_struct *target, const struct user_regset *regset, /* * These bits must be zero. */ - xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0; + memset(xsave_hdr->reserved, 0, 48); return ret; } -- cgit v1.2.2 From 47c2f292cc8669f70644a949cadd5fa5ee0e0e07 Mon Sep 17 00:00:00 2001 From: Fenghua Yu Date: Thu, 29 May 2014 11:12:42 -0700 Subject: x86/xsaves: Call booting time xsaves and xrstors in setup_init_fpu_buf setup_init_fpu_buf() calls booting time xsaves and xrstors to save and restore xstate in xsave area. Signed-off-by: Fenghua Yu Link: http://lkml.kernel.org/r/1401387164-43416-15-git-send-email-fenghua.yu@intel.com Signed-off-by: H. Peter Anvin --- arch/x86/kernel/xsave.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c index a4b451c6addf..8fa7c7d4183d 100644 --- a/arch/x86/kernel/xsave.c +++ b/arch/x86/kernel/xsave.c @@ -496,15 +496,21 @@ static void __init setup_init_fpu_buf(void) setup_xstate_features(); + if (cpu_has_xsaves) { + init_xstate_buf->xsave_hdr.xcomp_bv = + (u64)1 << 63 | pcntxt_mask; + init_xstate_buf->xsave_hdr.xstate_bv = pcntxt_mask; + } + /* * Init all the features state with header_bv being 0x0 */ - xrstor_state(init_xstate_buf, -1); + xrstor_state_booting(init_xstate_buf, -1); /* * Dump the init state again. This is to identify the init state * of any feature which is not represented by all zero's. */ - xsave_state(init_xstate_buf, -1); + xsave_state_booting(init_xstate_buf, -1); } static enum { AUTO, ENABLE, DISABLE } eagerfpu = AUTO; -- cgit v1.2.2 From 7e7ce87f6ad4e1730364e5e76628b43c5759b700 Mon Sep 17 00:00:00 2001 From: Fenghua Yu Date: Thu, 29 May 2014 11:12:43 -0700 Subject: x86/xsaves: Enable xsaves/xrstors If xsaves/xrstors is enabled, compacted format of xsave area will be used and less memory may be used for context per process. And modified optimization implemented in xsaves/xrstors improves performance of saving xstate. Signed-off-by: Fenghua Yu Link: http://lkml.kernel.org/r/1401387164-43416-16-git-send-email-fenghua.yu@intel.com Signed-off-by: H. Peter Anvin --- arch/x86/kernel/xsave.c | 39 +++++++++++++++++++++++++++++++++------ 1 file changed, 33 insertions(+), 6 deletions(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c index 8fa7c7d4183d..f930f8ab92d1 100644 --- a/arch/x86/kernel/xsave.c +++ b/arch/x86/kernel/xsave.c @@ -8,6 +8,7 @@ #include #include +#include #include #include #include @@ -24,7 +25,9 @@ u64 pcntxt_mask; struct xsave_struct *init_xstate_buf; static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32; -static unsigned int *xstate_offsets, *xstate_sizes, xstate_features; +static unsigned int *xstate_offsets, *xstate_sizes; +static unsigned int *xstate_comp_offsets, *xstate_comp_sizes; +static unsigned int xstate_features; /* * If a processor implementation discern that a processor state component is @@ -283,7 +286,7 @@ sanitize_restored_xstate(struct task_struct *tsk, if (use_xsave()) { /* These bits must be zero. */ - xsave_hdr->reserved1[0] = xsave_hdr->reserved1[1] = 0; + memset(xsave_hdr->reserved, 0, 48); /* * Init the state that is not present in the memory @@ -526,6 +529,30 @@ static int __init eager_fpu_setup(char *s) } __setup("eagerfpu=", eager_fpu_setup); + +/* + * Calculate total size of enabled xstates in XCR0/pcntxt_mask. + */ +static void __init init_xstate_size(void) +{ + unsigned int eax, ebx, ecx, edx; + int i; + + if (!cpu_has_xsaves) { + cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); + xstate_size = ebx; + return; + } + + xstate_size = FXSAVE_SIZE + XSAVE_HDR_SIZE; + for (i = 2; i < 64; i++) { + if (test_bit(i, (unsigned long *)&pcntxt_mask)) { + cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx); + xstate_size += eax; + } + } +} + /* * Enable and initialize the xsave feature. */ @@ -557,8 +584,7 @@ static void __init xstate_enable_boot_cpu(void) /* * Recompute the context size for enabled features */ - cpuid_count(XSTATE_CPUID, 0, &eax, &ebx, &ecx, &edx); - xstate_size = ebx; + init_xstate_size(); update_regset_xstate_info(xstate_size, pcntxt_mask); prepare_fx_sw_frame(); @@ -578,8 +604,9 @@ static void __init xstate_enable_boot_cpu(void) } } - pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x\n", - pcntxt_mask, xstate_size); + pr_info("enabled xstate_bv 0x%llx, cntxt size 0x%x using %s\n", + pcntxt_mask, xstate_size, + cpu_has_xsaves ? "compacted form" : "standard form"); } /* -- cgit v1.2.2 From 7496d6458fe3219d63848ce4a9afbd86245cab22 Mon Sep 17 00:00:00 2001 From: Fenghua Yu Date: Thu, 29 May 2014 11:12:44 -0700 Subject: Define kernel API to get address of each state in xsave area In standard form, each state is saved in the xsave area in fixed offset. But in compacted form, offset of each saved state only can be calculated during run time because some xstates may not be enabled and saved. We define kernel API get_xsave_addr() returns address of a given state saved in a xsave area. It can be called in kernel to get address of each xstate in xsave area in either standard format or compacted format. It's useful when kernel wants to directly access each state in xsave area. Signed-off-by: Fenghua Yu Link: http://lkml.kernel.org/r/1401387164-43416-17-git-send-email-fenghua.yu@intel.com Signed-off-by: H. Peter Anvin --- arch/x86/kernel/process.c | 1 + arch/x86/kernel/xsave.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 65 insertions(+) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 4505e2a950d8..f804dc935d2a 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -93,6 +93,7 @@ void arch_task_cache_init(void) kmem_cache_create("task_xstate", xstate_size, __alignof__(union thread_xstate), SLAB_PANIC | SLAB_NOTRACK, NULL); + setup_xstate_comp(); } /* diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c index f930f8ab92d1..a6cb8233f628 100644 --- a/arch/x86/kernel/xsave.c +++ b/arch/x86/kernel/xsave.c @@ -481,6 +481,47 @@ static void __init setup_xstate_features(void) } while (1); } +/* + * This function sets up offsets and sizes of all extended states in + * xsave area. This supports both standard format and compacted format + * of the xsave aread. + * + * Input: void + * Output: void + */ +void setup_xstate_comp(void) +{ + int i; + + xstate_comp_offsets = kmalloc(xstate_features * sizeof(int), + GFP_KERNEL); + xstate_comp_sizes = kmalloc(xstate_features * sizeof(int), GFP_KERNEL); + + if (!cpu_has_xsaves) { + for (i = 2; i < xstate_features; i++) { + if (test_bit(i, (unsigned long *)&pcntxt_mask)) { + xstate_comp_offsets[i] = xstate_offsets[i]; + xstate_comp_sizes[i] = xstate_sizes[i]; + } + } + return; + } + + xstate_comp_offsets[2] = FXSAVE_SIZE + XSAVE_HDR_SIZE; + + for (i = 2; i < xstate_features; i++) { + if (test_bit(i, (unsigned long *)&pcntxt_mask)) + xstate_comp_sizes[i] = xstate_sizes[i]; + else + xstate_comp_sizes[i] = 0; + + if (i > 2) + xstate_comp_offsets[i] = xstate_comp_offsets[i-1] + + xstate_comp_sizes[i-1]; + + } +} + /* * setup the xstate image representing the init state */ @@ -668,3 +709,26 @@ void eager_fpu_init(void) else fxrstor_checking(&init_xstate_buf->i387); } + +/* + * Given the xsave area and a state inside, this function returns the + * address of the state. + * + * This is the API that is called to get xstate address in either + * standard format or compacted format of xsave area. + * + * Inputs: + * xsave: base address of the xsave area; + * xstate: state which is defined in xsave.h (e.g. XSTATE_FP, XSTATE_SSE, + * etc.) + * Output: + * address of the state in the xsave area. + */ +void *get_xsave_addr(struct xsave_struct *xsave, int xstate) +{ + int feature = fls64(xstate) - 1; + if (!test_bit(feature, (unsigned long *)&pcntxt_mask)) + return NULL; + + return (void *)xsave + xstate_comp_offsets[feature]; +} -- cgit v1.2.2 From 8ff925e10f2c72680918b95173ef4f8bb982d59e Mon Sep 17 00:00:00 2001 From: Fenghua Yu Date: Fri, 30 May 2014 14:59:24 -0700 Subject: x86/xsaves: Clean up code in xstate offsets computation in xsave area This patch cleans up some code in xstate offsets computation in xsave area: 1. It changes xstate_comp_offsets as an array. This avoids possible NULL pointer caused by possible kmalloc() failure during boot time. 2. It changes the global variable xstate_comp_sizes to a local variable because it is used only in setup_xstate_comp(). 3. It adds missing offsets for FP and SSE in xsave area. Signed-off-by: Fenghua Yu Link: http://lkml.kernel.org/r/1401387164-43416-17-git-send-email-fenghua.yu@intel.com Signed-off-by: H. Peter Anvin --- arch/x86/kernel/xsave.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c index a6cb8233f628..940b142cc11f 100644 --- a/arch/x86/kernel/xsave.c +++ b/arch/x86/kernel/xsave.c @@ -26,7 +26,7 @@ struct xsave_struct *init_xstate_buf; static struct _fpx_sw_bytes fx_sw_reserved, fx_sw_reserved_ia32; static unsigned int *xstate_offsets, *xstate_sizes; -static unsigned int *xstate_comp_offsets, *xstate_comp_sizes; +static unsigned int xstate_comp_offsets[sizeof(pcntxt_mask)*8]; static unsigned int xstate_features; /* @@ -491,11 +491,16 @@ static void __init setup_xstate_features(void) */ void setup_xstate_comp(void) { + unsigned int xstate_comp_sizes[sizeof(pcntxt_mask)*8]; int i; - xstate_comp_offsets = kmalloc(xstate_features * sizeof(int), - GFP_KERNEL); - xstate_comp_sizes = kmalloc(xstate_features * sizeof(int), GFP_KERNEL); + /* + * The FP xstates and SSE xstates are legacy states. They are always + * in the fixed offsets in the xsave area in either compacted form + * or standard form. + */ + xstate_comp_offsets[0] = 0; + xstate_comp_offsets[1] = offsetof(struct i387_fxsave_struct, xmm_space); if (!cpu_has_xsaves) { for (i = 2; i < xstate_features; i++) { -- cgit v1.2.2