Merge branch 'core/urgent' into x86/fpu, to merge fixes
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 37babf9..459b301 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1074,12 +1074,6 @@
nopku [X86] Disable Memory Protection Keys CPU feature found
in some Intel CPUs.
- eagerfpu= [X86]
- on enable eager fpu restore
- off disable eager fpu restore
- auto selects the default scheme, which automatically
- enables eagerfpu restore for xsaveopt.
-
module.async_probe [KNL]
Enable asynchronous probe on this module.
diff --git a/arch/x86/crypto/crc32c-intel_glue.c b/arch/x86/crypto/crc32c-intel_glue.c
index 0857b1a..c194d57 100644
--- a/arch/x86/crypto/crc32c-intel_glue.c
+++ b/arch/x86/crypto/crc32c-intel_glue.c
@@ -48,26 +48,13 @@
#ifdef CONFIG_X86_64
/*
* use carryless multiply version of crc32c when buffer
- * size is >= 512 (when eager fpu is enabled) or
- * >= 1024 (when eager fpu is disabled) to account
+ * size is >= 512 to account
* for fpu state save/restore overhead.
*/
-#define CRC32C_PCL_BREAKEVEN_EAGERFPU 512
-#define CRC32C_PCL_BREAKEVEN_NOEAGERFPU 1024
+#define CRC32C_PCL_BREAKEVEN 512
asmlinkage unsigned int crc_pcl(const u8 *buffer, int len,
unsigned int crc_init);
-static int crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_EAGERFPU;
-#if defined(X86_FEATURE_EAGER_FPU)
-#define set_pcl_breakeven_point() \
-do { \
- if (!use_eager_fpu()) \
- crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_NOEAGERFPU; \
-} while (0)
-#else
-#define set_pcl_breakeven_point() \
- (crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_NOEAGERFPU)
-#endif
#endif /* CONFIG_X86_64 */
static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length)
@@ -190,7 +177,7 @@ static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
* use faster PCL version if datasize is large enough to
* overcome kernel fpu state save/restore overhead
*/
- if (len >= crc32c_pcl_breakeven && irq_fpu_usable()) {
+ if (len >= CRC32C_PCL_BREAKEVEN && irq_fpu_usable()) {
kernel_fpu_begin();
*crcp = crc_pcl(data, len, *crcp);
kernel_fpu_end();
@@ -202,7 +189,7 @@ static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
static int __crc32c_pcl_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
u8 *out)
{
- if (len >= crc32c_pcl_breakeven && irq_fpu_usable()) {
+ if (len >= CRC32C_PCL_BREAKEVEN && irq_fpu_usable()) {
kernel_fpu_begin();
*(__le32 *)out = ~cpu_to_le32(crc_pcl(data, len, *crcp));
kernel_fpu_end();
@@ -261,7 +248,6 @@ static int __init crc32c_intel_mod_init(void)
alg.update = crc32c_pcl_intel_update;
alg.finup = crc32c_pcl_intel_finup;
alg.digest = crc32c_pcl_intel_digest;
- set_pcl_breakeven_point();
}
#endif
return crypto_register_shash(&alg);
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index a396292..cddd5d0 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -104,7 +104,6 @@
#define X86_FEATURE_EXTD_APICID ( 3*32+26) /* has extended APICID (8 bits) */
#define X86_FEATURE_AMD_DCM ( 3*32+27) /* multi-node processor */
#define X86_FEATURE_APERFMPERF ( 3*32+28) /* APERFMPERF */
-#define X86_FEATURE_EAGER_FPU ( 3*32+29) /* "eagerfpu" Non lazy FPU restore */
#define X86_FEATURE_NONSTOP_TSC_S3 ( 3*32+30) /* TSC doesn't stop in S3 state */
/* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */
diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 2737366..d4a6849 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -60,11 +60,6 @@ extern u64 fpu__get_supported_xfeatures_mask(void);
/*
* FPU related CPU feature flag helper routines:
*/
-static __always_inline __pure bool use_eager_fpu(void)
-{
- return static_cpu_has(X86_FEATURE_EAGER_FPU);
-}
-
static __always_inline __pure bool use_xsaveopt(void)
{
return static_cpu_has(X86_FEATURE_XSAVEOPT);
@@ -484,42 +479,42 @@ extern int copy_fpstate_to_sigframe(void __user *buf, void __user *fp, int size)
DECLARE_PER_CPU(struct fpu *, fpu_fpregs_owner_ctx);
/*
- * Must be run with preemption disabled: this clears the fpu_fpregs_owner_ctx,
- * on this CPU.
+ * The in-register FPU state for an FPU context on a CPU is assumed to be
+ * valid if the fpu->last_cpu matches the CPU, and the fpu_fpregs_owner_ctx
+ * matches the FPU.
*
- * This will disable any lazy FPU state restore of the current FPU state,
- * but if the current thread owns the FPU, it will still be saved by.
+ * If the FPU register state is valid, the kernel can skip restoring the
+ * FPU state from memory.
+ *
+ * Any code that clobbers the FPU registers or updates the in-memory
+ * FPU state for a task MUST let the rest of the kernel know that the
+ * FPU registers are no longer valid for this task.
+ *
+ * Either one of these invalidation functions is enough. Invalidate
+ * a resource you control: CPU if using the CPU for something else
+ * (with preemption disabled), FPU for the current task, or a task that
+ * is prevented from running by the current task.
*/
-static inline void __cpu_disable_lazy_restore(unsigned int cpu)
+static inline void __cpu_invalidate_fpregs_state(void)
{
- per_cpu(fpu_fpregs_owner_ctx, cpu) = NULL;
+ __this_cpu_write(fpu_fpregs_owner_ctx, NULL);
}
-static inline int fpu_want_lazy_restore(struct fpu *fpu, unsigned int cpu)
+static inline void __fpu_invalidate_fpregs_state(struct fpu *fpu)
+{
+ fpu->last_cpu = -1;
+}
+
+static inline int fpregs_state_valid(struct fpu *fpu, unsigned int cpu)
{
return fpu == this_cpu_read_stable(fpu_fpregs_owner_ctx) && cpu == fpu->last_cpu;
}
-
/*
- * Wrap lazy FPU TS handling in a 'hw fpregs activation/deactivation'
- * idiom, which is then paired with the sw-flag (fpregs_active) later on:
+ * These generally need preemption protection to work,
+ * do try to avoid using these on their own:
*/
-
-static inline void __fpregs_activate_hw(void)
-{
- if (!use_eager_fpu())
- clts();
-}
-
-static inline void __fpregs_deactivate_hw(void)
-{
- if (!use_eager_fpu())
- stts();
-}
-
-/* Must be paired with an 'stts' (fpregs_deactivate_hw()) after! */
-static inline void __fpregs_deactivate(struct fpu *fpu)
+static inline void fpregs_deactivate(struct fpu *fpu)
{
WARN_ON_FPU(!fpu->fpregs_active);
@@ -528,8 +523,7 @@ static inline void __fpregs_deactivate(struct fpu *fpu)
trace_x86_fpu_regs_deactivated(fpu);
}
-/* Must be paired with a 'clts' (fpregs_activate_hw()) before! */
-static inline void __fpregs_activate(struct fpu *fpu)
+static inline void fpregs_activate(struct fpu *fpu)
{
WARN_ON_FPU(fpu->fpregs_active);
@@ -554,51 +548,19 @@ static inline int fpregs_active(void)
}
/*
- * Encapsulate the CR0.TS handling together with the
- * software flag.
- *
- * These generally need preemption protection to work,
- * do try to avoid using these on their own.
- */
-static inline void fpregs_activate(struct fpu *fpu)
-{
- __fpregs_activate_hw();
- __fpregs_activate(fpu);
-}
-
-static inline void fpregs_deactivate(struct fpu *fpu)
-{
- __fpregs_deactivate(fpu);
- __fpregs_deactivate_hw();
-}
-
-/*
* FPU state switching for scheduling.
*
* This is a two-stage process:
*
- * - switch_fpu_prepare() saves the old state and
- * sets the new state of the CR0.TS bit. This is
- * done within the context of the old process.
+ * - switch_fpu_prepare() saves the old state.
+ * This is done within the context of the old process.
*
* - switch_fpu_finish() restores the new state as
* necessary.
*/
-typedef struct { int preload; } fpu_switch_t;
-
-static inline fpu_switch_t
-switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu)
+static inline void
+switch_fpu_prepare(struct fpu *old_fpu, int cpu)
{
- fpu_switch_t fpu;
-
- /*
- * If the task has used the math, pre-load the FPU on xsave processors
- * or if the past 5 consecutive context-switches used math.
- */
- fpu.preload = static_cpu_has(X86_FEATURE_FPU) &&
- new_fpu->fpstate_active &&
- (use_eager_fpu() || new_fpu->counter > 5);
-
if (old_fpu->fpregs_active) {
if (!copy_fpregs_to_fpstate(old_fpu))
old_fpu->last_cpu = -1;
@@ -608,29 +570,8 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu)
/* But leave fpu_fpregs_owner_ctx! */
old_fpu->fpregs_active = 0;
trace_x86_fpu_regs_deactivated(old_fpu);
-
- /* Don't change CR0.TS if we just switch! */
- if (fpu.preload) {
- new_fpu->counter++;
- __fpregs_activate(new_fpu);
- trace_x86_fpu_regs_activated(new_fpu);
- prefetch(&new_fpu->state);
- } else {
- __fpregs_deactivate_hw();
- }
- } else {
- old_fpu->counter = 0;
+ } else
old_fpu->last_cpu = -1;
- if (fpu.preload) {
- new_fpu->counter++;
- if (fpu_want_lazy_restore(new_fpu, cpu))
- fpu.preload = 0;
- else
- prefetch(&new_fpu->state);
- fpregs_activate(new_fpu);
- }
- }
- return fpu;
}
/*
@@ -638,15 +579,19 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu)
*/
/*
- * By the time this gets called, we've already cleared CR0.TS and
- * given the process the FPU if we are going to preload the FPU
- * state - all we need to do is to conditionally restore the register
- * state itself.
+ * Set up the userspace FPU context for the new task, if the task
+ * has used the FPU.
*/
-static inline void switch_fpu_finish(struct fpu *new_fpu, fpu_switch_t fpu_switch)
+static inline void switch_fpu_finish(struct fpu *new_fpu, int cpu)
{
- if (fpu_switch.preload)
- copy_kernel_to_fpregs(&new_fpu->state);
+ bool preload = static_cpu_has(X86_FEATURE_FPU) &&
+ new_fpu->fpstate_active;
+
+ if (preload) {
+ if (!fpregs_state_valid(new_fpu, cpu))
+ copy_kernel_to_fpregs(&new_fpu->state);
+ fpregs_activate(new_fpu);
+ }
}
/*
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h
index 48df486..3c80f5b 100644
--- a/arch/x86/include/asm/fpu/types.h
+++ b/arch/x86/include/asm/fpu/types.h
@@ -322,17 +322,6 @@ struct fpu {
unsigned char fpregs_active;
/*
- * @counter:
- *
- * This counter contains the number of consecutive context switches
- * during which the FPU stays used. If this is over a threshold, the
- * lazy FPU restore logic becomes eager, to save the trap overhead.
- * This is an unsigned char so that after 256 iterations the counter
- * wraps and the context switch behavior turns lazy again; this is to
- * deal with bursty apps that only use the FPU for a short time:
- */
- unsigned char counter;
- /*
* @state:
*
* In-memory copy of all FPU registers that we save/restore
@@ -340,29 +329,6 @@ struct fpu {
* the registers in the FPU are more recent than this state
* copy. If the task context-switches away then they get
* saved here and represent the FPU state.
- *
- * After context switches there may be a (short) time period
- * during which the in-FPU hardware registers are unchanged
- * and still perfectly match this state, if the tasks
- * scheduled afterwards are not using the FPU.
- *
- * This is the 'lazy restore' window of optimization, which
- * we track though 'fpu_fpregs_owner_ctx' and 'fpu->last_cpu'.
- *
- * We detect whether a subsequent task uses the FPU via setting
- * CR0::TS to 1, which causes any FPU use to raise a #NM fault.
- *
- * During this window, if the task gets scheduled again, we
- * might be able to skip having to do a restore from this
- * memory buffer to the hardware registers - at the cost of
- * incurring the overhead of #NM fault traps.
- *
- * Note that on modern CPUs that support the XSAVEOPT (or other
- * optimized XSAVE instructions), we don't use #NM traps anymore,
- * as the hardware can track whether FPU registers need saving
- * or not. On such CPUs we activate the non-lazy ('eagerfpu')
- * logic, which unconditionally saves/restores all FPU state
- * across context switches. (if FPU state exists.)
*/
union fpregs_state state;
/*
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index 430bacf..1b2799e 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -21,21 +21,16 @@
/* Supervisor features */
#define XFEATURE_MASK_SUPERVISOR (XFEATURE_MASK_PT)
-/* Supported features which support lazy state saving */
-#define XFEATURE_MASK_LAZY (XFEATURE_MASK_FP | \
+/* All currently supported features */
+#define XCNTXT_MASK (XFEATURE_MASK_FP | \
XFEATURE_MASK_SSE | \
XFEATURE_MASK_YMM | \
XFEATURE_MASK_OPMASK | \
XFEATURE_MASK_ZMM_Hi256 | \
- XFEATURE_MASK_Hi16_ZMM)
-
-/* Supported features which require eager state saving */
-#define XFEATURE_MASK_EAGER (XFEATURE_MASK_BNDREGS | \
- XFEATURE_MASK_BNDCSR | \
- XFEATURE_MASK_PKRU)
-
-/* All currently supported features */
-#define XCNTXT_MASK (XFEATURE_MASK_LAZY | XFEATURE_MASK_EAGER)
+ XFEATURE_MASK_Hi16_ZMM | \
+ XFEATURE_MASK_PKRU | \
+ XFEATURE_MASK_BNDREGS | \
+ XFEATURE_MASK_BNDCSR)
#ifdef CONFIG_X86_64
#define REX_PREFIX "0x48, "
diff --git a/arch/x86/include/asm/trace/fpu.h b/arch/x86/include/asm/trace/fpu.h
index 9217ab1..342e597 100644
--- a/arch/x86/include/asm/trace/fpu.h
+++ b/arch/x86/include/asm/trace/fpu.h
@@ -14,7 +14,6 @@ DECLARE_EVENT_CLASS(x86_fpu,
__field(struct fpu *, fpu)
__field(bool, fpregs_active)
__field(bool, fpstate_active)
- __field(int, counter)
__field(u64, xfeatures)
__field(u64, xcomp_bv)
),
@@ -23,17 +22,15 @@ DECLARE_EVENT_CLASS(x86_fpu,
__entry->fpu = fpu;
__entry->fpregs_active = fpu->fpregs_active;
__entry->fpstate_active = fpu->fpstate_active;
- __entry->counter = fpu->counter;
if (boot_cpu_has(X86_FEATURE_OSXSAVE)) {
__entry->xfeatures = fpu->state.xsave.header.xfeatures;
__entry->xcomp_bv = fpu->state.xsave.header.xcomp_bv;
}
),
- TP_printk("x86/fpu: %p fpregs_active: %d fpstate_active: %d counter: %d xfeatures: %llx xcomp_bv: %llx",
+ TP_printk("x86/fpu: %p fpregs_active: %d fpstate_active: %d xfeatures: %llx xcomp_bv: %llx",
__entry->fpu,
__entry->fpregs_active,
__entry->fpstate_active,
- __entry->counter,
__entry->xfeatures,
__entry->xcomp_bv
)
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 4700401..52f56844 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -58,27 +58,9 @@ static bool kernel_fpu_disabled(void)
return this_cpu_read(in_kernel_fpu);
}
-/*
- * Were we in an interrupt that interrupted kernel mode?
- *
- * On others, we can do a kernel_fpu_begin/end() pair *ONLY* if that
- * pair does nothing at all: the thread must not have fpu (so
- * that we don't try to save the FPU state), and TS must
- * be set (so that the clts/stts pair does nothing that is
- * visible in the interrupted kernel thread).
- *
- * Except for the eagerfpu case when we return true; in the likely case
- * the thread has FPU but we are not going to set/clear TS.
- */
static bool interrupted_kernel_fpu_idle(void)
{
- if (kernel_fpu_disabled())
- return false;
-
- if (use_eager_fpu())
- return true;
-
- return !current->thread.fpu.fpregs_active && (read_cr0() & X86_CR0_TS);
+ return !kernel_fpu_disabled();
}
/*
@@ -125,8 +107,7 @@ void __kernel_fpu_begin(void)
*/
copy_fpregs_to_fpstate(fpu);
} else {
- this_cpu_write(fpu_fpregs_owner_ctx, NULL);
- __fpregs_activate_hw();
+ __cpu_invalidate_fpregs_state();
}
}
EXPORT_SYMBOL(__kernel_fpu_begin);
@@ -137,8 +118,6 @@ void __kernel_fpu_end(void)
if (fpu->fpregs_active)
copy_kernel_to_fpregs(&fpu->state);
- else
- __fpregs_deactivate_hw();
kernel_fpu_enable();
}
@@ -200,10 +179,7 @@ void fpu__save(struct fpu *fpu)
trace_x86_fpu_before_save(fpu);
if (fpu->fpregs_active) {
if (!copy_fpregs_to_fpstate(fpu)) {
- if (use_eager_fpu())
- copy_kernel_to_fpregs(&fpu->state);
- else
- fpregs_deactivate(fpu);
+ copy_kernel_to_fpregs(&fpu->state);
}
}
trace_x86_fpu_after_save(fpu);
@@ -247,7 +223,6 @@ EXPORT_SYMBOL_GPL(fpstate_init);
int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
{
- dst_fpu->counter = 0;
dst_fpu->fpregs_active = 0;
dst_fpu->last_cpu = -1;
@@ -260,8 +235,7 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
* Don't let 'init optimized' areas of the XSAVE area
* leak into the child task:
*/
- if (use_eager_fpu())
- memset(&dst_fpu->state.xsave, 0, fpu_kernel_xstate_size);
+ memset(&dst_fpu->state.xsave, 0, fpu_kernel_xstate_size);
/*
* Save current FPU registers directly into the child
@@ -283,10 +257,7 @@ int fpu__copy(struct fpu *dst_fpu, struct fpu *src_fpu)
memcpy(&src_fpu->state, &dst_fpu->state,
fpu_kernel_xstate_size);
- if (use_eager_fpu())
- copy_kernel_to_fpregs(&src_fpu->state);
- else
- fpregs_deactivate(src_fpu);
+ copy_kernel_to_fpregs(&src_fpu->state);
}
preempt_enable();
@@ -366,7 +337,7 @@ void fpu__activate_fpstate_write(struct fpu *fpu)
if (fpu->fpstate_active) {
/* Invalidate any lazy state: */
- fpu->last_cpu = -1;
+ __fpu_invalidate_fpregs_state(fpu);
} else {
fpstate_init(&fpu->state);
trace_x86_fpu_init_state(fpu);
@@ -409,7 +380,7 @@ void fpu__current_fpstate_write_begin(void)
* ensures we will not be lazy and skip a XRSTOR in the
* future.
*/
- fpu->last_cpu = -1;
+ __fpu_invalidate_fpregs_state(fpu);
}
/*
@@ -459,7 +430,6 @@ void fpu__restore(struct fpu *fpu)
trace_x86_fpu_before_restore(fpu);
fpregs_activate(fpu);
copy_kernel_to_fpregs(&fpu->state);
- fpu->counter++;
trace_x86_fpu_after_restore(fpu);
kernel_fpu_enable();
}
@@ -477,7 +447,6 @@ EXPORT_SYMBOL_GPL(fpu__restore);
void fpu__drop(struct fpu *fpu)
{
preempt_disable();
- fpu->counter = 0;
if (fpu->fpregs_active) {
/* Ignore delayed exceptions from user space */
@@ -521,7 +490,7 @@ void fpu__clear(struct fpu *fpu)
{
WARN_ON_FPU(fpu != ¤t->thread.fpu); /* Almost certainly an anomaly */
- if (!use_eager_fpu() || !static_cpu_has(X86_FEATURE_FPU)) {
+ if (!static_cpu_has(X86_FEATURE_FPU)) {
/* FPU state will be reallocated lazily at the first use. */
fpu__drop(fpu);
} else {
diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c
index 2f2b8c7..1a09d13 100644
--- a/arch/x86/kernel/fpu/init.c
+++ b/arch/x86/kernel/fpu/init.c
@@ -15,10 +15,7 @@
*/
static void fpu__init_cpu_ctx_switch(void)
{
- if (!boot_cpu_has(X86_FEATURE_EAGER_FPU))
- stts();
- else
- clts();
+ clts();
}
/*
@@ -233,82 +230,16 @@ static void __init fpu__init_system_xstate_size_legacy(void)
}
/*
- * FPU context switching strategies:
- *
- * Against popular belief, we don't do lazy FPU saves, due to the
- * task migration complications it brings on SMP - we only do
- * lazy FPU restores.
- *
- * 'lazy' is the traditional strategy, which is based on setting
- * CR0::TS to 1 during context-switch (instead of doing a full
- * restore of the FPU state), which causes the first FPU instruction
- * after the context switch (whenever it is executed) to fault - at
- * which point we lazily restore the FPU state into FPU registers.
- *
- * Tasks are of course under no obligation to execute FPU instructions,
- * so it can easily happen that another context-switch occurs without
- * a single FPU instruction being executed. If we eventually switch
- * back to the original task (that still owns the FPU) then we have
- * not only saved the restores along the way, but we also have the
- * FPU ready to be used for the original task.
- *
- * 'lazy' is deprecated because it's almost never a performance win
- * and it's much more complicated than 'eager'.
- *
- * 'eager' switching is by default on all CPUs, there we switch the FPU
- * state during every context switch, regardless of whether the task
- * has used FPU instructions in that time slice or not. This is done
- * because modern FPU context saving instructions are able to optimize
- * state saving and restoration in hardware: they can detect both
- * unused and untouched FPU state and optimize accordingly.
- *
- * [ Note that even in 'lazy' mode we might optimize context switches
- * to use 'eager' restores, if we detect that a task is using the FPU
- * frequently. See the fpu->counter logic in fpu/internal.h for that. ]
- */
-static enum { ENABLE, DISABLE } eagerfpu = ENABLE;
-
-/*
* Find supported xfeatures based on cpu features and command-line input.
* This must be called after fpu__init_parse_early_param() is called and
* xfeatures_mask is enumerated.
*/
u64 __init fpu__get_supported_xfeatures_mask(void)
{
- /* Support all xfeatures known to us */
- if (eagerfpu != DISABLE)
- return XCNTXT_MASK;
-
- /* Warning of xfeatures being disabled for no eagerfpu mode */
- if (xfeatures_mask & XFEATURE_MASK_EAGER) {
- pr_err("x86/fpu: eagerfpu switching disabled, disabling the following xstate features: 0x%llx.\n",
- xfeatures_mask & XFEATURE_MASK_EAGER);
- }
-
- /* Return a mask that masks out all features requiring eagerfpu mode */
- return ~XFEATURE_MASK_EAGER;
+ return XCNTXT_MASK;
}
-/*
- * Disable features dependent on eagerfpu.
- */
-static void __init fpu__clear_eager_fpu_features(void)
-{
- setup_clear_cpu_cap(X86_FEATURE_MPX);
-}
-
-/*
- * Pick the FPU context switching strategy:
- *
- * When eagerfpu is AUTO or ENABLE, we ensure it is ENABLE if either of
- * the following is true:
- *
- * (1) the cpu has xsaveopt, as it has the optimization and doing eager
- * FPU switching has a relatively low cost compared to a plain xsave;
- * (2) the cpu has xsave features (e.g. MPX) that depend on eager FPU
- * switching. Should the kernel boot with noxsaveopt, we support MPX
- * with eager FPU switching at a higher cost.
- */
+/* Legacy code to initialize eager fpu mode. */
static void __init fpu__init_system_ctx_switch(void)
{
static bool on_boot_cpu __initdata = 1;
@@ -317,17 +248,6 @@ static void __init fpu__init_system_ctx_switch(void)
on_boot_cpu = 0;
WARN_ON_FPU(current->thread.fpu.fpstate_active);
-
- if (boot_cpu_has(X86_FEATURE_XSAVEOPT) && eagerfpu != DISABLE)
- eagerfpu = ENABLE;
-
- if (xfeatures_mask & XFEATURE_MASK_EAGER)
- eagerfpu = ENABLE;
-
- if (eagerfpu == ENABLE)
- setup_force_cpu_cap(X86_FEATURE_EAGER_FPU);
-
- printk(KERN_INFO "x86/fpu: Using '%s' FPU context switches.\n", eagerfpu == ENABLE ? "eager" : "lazy");
}
/*
@@ -336,11 +256,6 @@ static void __init fpu__init_system_ctx_switch(void)
*/
static void __init fpu__init_parse_early_param(void)
{
- if (cmdline_find_option_bool(boot_command_line, "eagerfpu=off")) {
- eagerfpu = DISABLE;
- fpu__clear_eager_fpu_features();
- }
-
if (cmdline_find_option_bool(boot_command_line, "no387"))
setup_clear_cpu_cap(X86_FEATURE_FPU);
diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c
index a184c21..83c23c2 100644
--- a/arch/x86/kernel/fpu/signal.c
+++ b/arch/x86/kernel/fpu/signal.c
@@ -340,11 +340,9 @@ static int __fpu__restore_sig(void __user *buf, void __user *buf_fx, int size)
}
fpu->fpstate_active = 1;
- if (use_eager_fpu()) {
- preempt_disable();
- fpu__restore(fpu);
- preempt_enable();
- }
+ preempt_disable();
+ fpu__restore(fpu);
+ preempt_enable();
return err;
} else {
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 095ef7d..c7c11cc 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -890,15 +890,6 @@ int arch_set_user_pkey_access(struct task_struct *tsk, int pkey,
*/
if (!boot_cpu_has(X86_FEATURE_OSPKE))
return -EINVAL;
- /*
- * For most XSAVE components, this would be an arduous task:
- * brining fpstate up to date with fpregs, updating fpstate,
- * then re-populating fpregs. But, for components that are
- * never lazily managed, we can just access the fpregs
- * directly. PKRU is never managed lazily, so we can just
- * manipulate it directly. Make sure it stays that way.
- */
- WARN_ON_ONCE(!use_eager_fpu());
/* Set the bits we need in PKRU: */
if (init_val & PKEY_DISABLE_ACCESS)
diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index bd7be8e..7dc8c9c 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -232,11 +232,10 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
struct fpu *next_fpu = &next->fpu;
int cpu = smp_processor_id();
struct tss_struct *tss = &per_cpu(cpu_tss, cpu);
- fpu_switch_t fpu_switch;
/* never put a printk in __switch_to... printk() calls wake_up*() indirectly */
- fpu_switch = switch_fpu_prepare(prev_fpu, next_fpu, cpu);
+ switch_fpu_prepare(prev_fpu, cpu);
/*
* Save away %gs. No need to save %fs, as it was saved on the
@@ -295,7 +294,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
if (prev->gs | next->gs)
lazy_load_gs(next->gs);
- switch_fpu_finish(next_fpu, fpu_switch);
+ switch_fpu_finish(next_fpu, cpu);
this_cpu_write(current_task, next_p);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index b3760b3..9c3a7b0 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -265,9 +265,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
int cpu = smp_processor_id();
struct tss_struct *tss = &per_cpu(cpu_tss, cpu);
unsigned prev_fsindex, prev_gsindex;
- fpu_switch_t fpu_switch;
- fpu_switch = switch_fpu_prepare(prev_fpu, next_fpu, cpu);
+ switch_fpu_prepare(prev_fpu, cpu);
/* We must save %fs and %gs before load_TLS() because
* %fs and %gs may be cleared by load_TLS().
@@ -417,7 +416,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
prev->gsbase = 0;
prev->gsindex = prev_gsindex;
- switch_fpu_finish(next_fpu, fpu_switch);
+ switch_fpu_finish(next_fpu, cpu);
/*
* Switch the PDA and FPU contexts.
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 42f5eb7..d29c852 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1111,7 +1111,7 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
return err;
/* the FPU context is blank, nobody can own it */
- __cpu_disable_lazy_restore(cpu);
+ per_cpu(fpu_fpregs_owner_ctx, cpu) = NULL;
common_cpu_up(cpu, tidle);
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index afa7bbb..0aefb62 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -16,7 +16,6 @@
#include <linux/export.h>
#include <linux/vmalloc.h>
#include <linux/uaccess.h>
-#include <asm/fpu/internal.h> /* For use_eager_fpu. Ugh! */
#include <asm/user.h>
#include <asm/fpu/xstate.h>
#include "cpuid.h"
@@ -114,8 +113,7 @@ int kvm_update_cpuid(struct kvm_vcpu *vcpu)
if (best && (best->eax & (F(XSAVES) | F(XSAVEC))))
best->ebx = xstate_required_size(vcpu->arch.xcr0, true);
- if (use_eager_fpu())
- kvm_x86_ops->fpu_activate(vcpu);
+ kvm_x86_ops->fpu_activate(vcpu);
/*
* The existing code assumes virtual address is 48-bit in the canonical
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index e375235..7f9fa2d 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7386,25 +7386,13 @@ void kvm_load_guest_fpu(struct kvm_vcpu *vcpu)
void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
{
- if (!vcpu->guest_fpu_loaded) {
- vcpu->fpu_counter = 0;
+ if (!vcpu->guest_fpu_loaded)
return;
- }
vcpu->guest_fpu_loaded = 0;
copy_fpregs_to_fpstate(&vcpu->arch.guest_fpu);
__kernel_fpu_end();
++vcpu->stat.fpu_reload;
- /*
- * If using eager FPU mode, or if the guest is a frequent user
- * of the FPU, just leave the FPU active for next time.
- * Every 255 times fpu_counter rolls over to 0; a guest that uses
- * the FPU in bursts will revert to loading it on demand.
- */
- if (!use_eager_fpu()) {
- if (++vcpu->fpu_counter < 5)
- kvm_make_request(KVM_REQ_DEACTIVATE_FPU, vcpu);
- }
trace_kvm_fpu(0);
}
diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c
index f88ce0e..2dab69a 100644
--- a/arch/x86/mm/pkeys.c
+++ b/arch/x86/mm/pkeys.c
@@ -141,8 +141,7 @@ u32 init_pkru_value = PKRU_AD_KEY( 1) | PKRU_AD_KEY( 2) | PKRU_AD_KEY( 3) |
* Called from the FPU code when creating a fresh set of FPU
* registers. This is called from a very specific context where
* we know the FPU regstiers are safe for use and we can use PKRU
- * directly. The fact that PKRU is only available when we are
- * using eagerfpu mode makes this possible.
+ * directly.
*/
void copy_init_pkru_to_fpregs(void)
{
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 01c0b9c..cfc212d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -224,7 +224,6 @@ struct kvm_vcpu {
int fpu_active;
int guest_fpu_loaded, guest_xcr0_loaded;
- unsigned char fpu_counter;
struct swait_queue_head wq;
struct pid *pid;
int sigset_active;
diff --git a/tools/arch/x86/include/asm/cpufeatures.h b/tools/arch/x86/include/asm/cpufeatures.h
index a396292..cddd5d0 100644
--- a/tools/arch/x86/include/asm/cpufeatures.h
+++ b/tools/arch/x86/include/asm/cpufeatures.h
@@ -104,7 +104,6 @@
#define X86_FEATURE_EXTD_APICID ( 3*32+26) /* has extended APICID (8 bits) */
#define X86_FEATURE_AMD_DCM ( 3*32+27) /* multi-node processor */
#define X86_FEATURE_APERFMPERF ( 3*32+28) /* APERFMPERF */
-#define X86_FEATURE_EAGER_FPU ( 3*32+29) /* "eagerfpu" Non lazy FPU restore */
#define X86_FEATURE_NONSTOP_TSC_S3 ( 3*32+30) /* TSC doesn't stop in S3 state */
/* Intel-defined CPU features, CPUID level 0x00000001 (ecx), word 4 */