From: Andy Lutomirski luto@kernel.org

commit c592b57347069abfc0dcad3b3a302cf882602597 upstream

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 Signed-off-by: Daniel Sangorrin daniel.sangorrin@toshiba.co.jp --- arch/x86/crypto/crc32c-intel_glue.c | 17 ++++------------- arch/x86/include/asm/fpu/internal.h | 34 +--------------------------------- arch/x86/kernel/fpu/core.c | 36 ++++-------------------------------- 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, 13 insertions(+), 105 deletions(-)

diff --git a/arch/x86/crypto/crc32c-intel_glue.c b/arch/x86/crypto/crc32c-intel_glue.c index dd19584..5773e11 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(); @@ -257,7 +249,6 @@ 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 96d80df..2dc1927 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(); }

/* @@ -126,7 +108,6 @@ 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); @@ -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); @@ -261,8 +237,7 @@ 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 @@ -284,10 +259,7 @@ 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();

diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c index 3ec0d2d..3a93186 100644 --- a/arch/x86/kernel/fpu/signal.c +++ b/arch/x86/kernel/fpu/signal.c @@ -344,11 +344,9 @@ 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 abfbb61b..e9d7f46 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/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 7e5119c..c17d389 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 5ca23af..0754dae 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -7513,16 +7513,6 @@ 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); }