From: tip-bot for Andy Lutomirski <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: peterz@infradead.org, luto@kernel.org, dvlasenk@redhat.com,
riel@redhat.com, brgerst@gmail.com, jpoimboe@redhat.com,
oleg@redhat.com, torvalds@linux-foundation.org,
tglx@linutronix.de, quentin.casasnovas@oracle.com,
linux-kernel@vger.kernel.org, mingo@kernel.org, hpa@zytor.com,
bp@alien8.de, fenghua.yu@intel.com, dave.hansen@linux.intel.com
Subject: [tip:x86/fpu] x86/fpu: Remove use_eager_fpu()
Date: Fri, 7 Oct 2016 02:44:43 -0700 [thread overview]
Message-ID: <tip-c592b57347069abfc0dcad3b3a302cf882602597@git.kernel.org> (raw)
In-Reply-To: <1475627678-20788-5-git-send-email-riel@redhat.com>
Commit-ID: c592b57347069abfc0dcad3b3a302cf882602597
Gitweb: http://git.kernel.org/tip/c592b57347069abfc0dcad3b3a302cf882602597
Author: Andy Lutomirski <luto@kernel.org>
AuthorDate: Tue, 4 Oct 2016 20:34:33 -0400
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Fri, 7 Oct 2016 11:14:36 +0200
x86/fpu: Remove use_eager_fpu()
This removes all the obvious code paths that depend on lazy FPU mode.
It shouldn't change the generated code at all.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Quentin Casasnovas <quentin.casasnovas@oracle.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: pbonzini@redhat.com
Link: http://lkml.kernel.org/r/1475627678-20788-5-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/crypto/crc32c-intel_glue.c | 17 ++++-------------
arch/x86/include/asm/fpu/internal.h | 34 +--------------------------------
arch/x86/kernel/fpu/core.c | 38 +++++--------------------------------
arch/x86/kernel/fpu/signal.c | 8 +++-----
arch/x86/kernel/fpu/xstate.c | 9 ---------
arch/x86/kvm/cpuid.c | 4 +---
arch/x86/kvm/x86.c | 10 ----------
7 files changed, 14 insertions(+), 106 deletions(-)
diff --git a/arch/x86/crypto/crc32c-intel_glue.c b/arch/x86/crypto/crc32c-intel_glue.c
index 715399b..c194d57 100644
--- a/arch/x86/crypto/crc32c-intel_glue.c
+++ b/arch/x86/crypto/crc32c-intel_glue.c
@@ -48,21 +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;
-#define set_pcl_breakeven_point() \
-do { \
- if (!use_eager_fpu()) \
- crc32c_pcl_breakeven = CRC32C_PCL_BREAKEVEN_NOEAGERFPU; \
-} while (0)
#endif /* CONFIG_X86_64 */
static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length)
@@ -185,7 +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();
@@ -197,7 +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();
@@ -256,7 +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/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index 8852e3a..7801d32 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 true;
-}
-
static __always_inline __pure bool use_xsaveopt(void)
{
return static_cpu_has(X86_FEATURE_XSAVEOPT);
@@ -501,24 +496,6 @@ static inline int fpu_want_lazy_restore(struct fpu *fpu, unsigned int 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:
- */
-
-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)
{
WARN_ON_FPU(!fpu->fpregs_active);
@@ -528,7 +505,6 @@ 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)
{
WARN_ON_FPU(fpu->fpregs_active);
@@ -554,22 +530,17 @@ 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();
}
/*
@@ -596,8 +567,7 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu)
* 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);
+ new_fpu->fpstate_active;
if (old_fpu->fpregs_active) {
if (!copy_fpregs_to_fpstate(old_fpu))
@@ -615,8 +585,6 @@ switch_fpu_prepare(struct fpu *old_fpu, struct fpu *new_fpu, int cpu)
__fpregs_activate(new_fpu);
trace_x86_fpu_regs_activated(new_fpu);
prefetch(&new_fpu->state);
- } else {
- __fpregs_deactivate_hw();
}
} else {
old_fpu->counter = 0;
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c
index 3fc03a0..036e14f 100644
--- a/arch/x86/kernel/fpu/core.c
+++ b/arch/x86/kernel/fpu/core.c
@@ -57,27 +57,9 @@ 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();
}
/*
@@ -125,7 +107,6 @@ void __kernel_fpu_begin(void)
copy_fpregs_to_fpstate(fpu);
} else {
this_cpu_write(fpu_fpregs_owner_ctx, NULL);
- __fpregs_activate_hw();
}
}
EXPORT_SYMBOL(__kernel_fpu_begin);
@@ -136,8 +117,6 @@ void __kernel_fpu_end(void)
if (fpu->fpregs_active)
copy_kernel_to_fpregs(&fpu->state);
- else
- __fpregs_deactivate_hw();
kernel_fpu_enable();
}
@@ -199,10 +178,7 @@ 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);
@@ -259,8 +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
@@ -282,10 +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();
@@ -517,7 +489,7 @@ 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/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 01567aa..76bc2a1 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -886,15 +886,6 @@ 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/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 3235e0f..1cf143e 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 699f872..59d7761 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7357,16 +7357,6 @@ void kvm_put_guest_fpu(struct kvm_vcpu *vcpu)
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);
}
next prev parent reply other threads:[~2016-10-07 9:47 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-05 0:34 [PATCH 0/9] x86/fpu: remove lazy FPU mode & various FPU cleanups riel
2016-10-05 0:34 ` [PATCH 1/9] x86/crypto: Remove X86_FEATURE_EAGER_FPU ifdef from the crc32c code riel
2016-10-05 0:40 ` Rik van Riel
2016-10-07 9:43 ` [tip:x86/fpu] x86/crypto, x86/fpu: Remove X86_FEATURE_EAGER_FPU #ifdef " tip-bot for Andy Lutomirski
2016-10-05 0:34 ` [PATCH 2/9] x86/fpu: Hard-disable lazy fpu mode riel
2016-10-05 7:14 ` Paolo Bonzini
2016-10-05 13:57 ` Rik van Riel
2016-10-05 14:03 ` Paolo Bonzini
2016-10-05 15:59 ` Andy Lutomirski
2016-10-05 16:09 ` Paolo Bonzini
2016-10-07 9:43 ` [tip:x86/fpu] x86/fpu: Hard-disable lazy FPU mode tip-bot for Andy Lutomirski
2016-10-05 0:34 ` [PATCH 3/9] x86/fpu: Remove the XFEATURE_MASK_EAGER/LAZY distinction riel
2016-10-07 9:44 ` [tip:x86/fpu] " tip-bot for Andy Lutomirski
2016-10-05 0:34 ` [PATCH 4/9] x86/fpu: Remove use_eager_fpu() riel
2016-10-07 9:44 ` tip-bot for Andy Lutomirski [this message]
2016-10-05 0:34 ` [PATCH 5/9] x86/fpu: remove fpu.counter riel
2016-10-05 2:07 ` Andy Lutomirski
2016-10-07 9:45 ` [tip:x86/fpu] x86/fpu: Remove struct fpu::counter tip-bot for Rik van Riel
2016-10-05 0:34 ` [PATCH 6/9] x86/fpu,kvm: remove kvm vcpu->fpu_counter riel
2016-10-07 9:45 ` [tip:x86/fpu] x86/fpu, kvm: Remove KVM vcpu->fpu_counter tip-bot for Rik van Riel
2016-10-05 0:34 ` [PATCH 7/9] x86/fpu: rename lazy restore functions to "register state valid" riel
2016-10-05 2:09 ` Andy Lutomirski
2016-10-07 9:46 ` [tip:x86/fpu] x86/fpu: Rename " tip-bot for Rik van Riel
2016-10-05 0:34 ` [PATCH 8/9] x86/fpu: remove __fpregs_(de)activate riel
2016-10-05 2:10 ` Andy Lutomirski
2016-10-07 9:46 ` [tip:x86/fpu] x86/fpu: Remove __fpregs_(de)activate() tip-bot for Rik van Riel
2016-10-05 0:34 ` [PATCH 9/9] x86/fpu: split old & new fpu code paths riel
2016-10-07 9:47 ` [tip:x86/fpu] x86/fpu: Split old & new FPU " tip-bot for Rik van Riel
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