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x86: Store a per-cpu shadow copy of CR4

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Context switches and TLB flushes can change individual bits of CR4.
CR4 reads take several cycles, so store a shadow copy of CR4 in a
per-cpu variable.

To avoid wasting a cache line, I added the CR4 shadow to
cpu_tlbstate, which is already touched in switch_mm.  The heaviest
users of the cr4 shadow will be switch_mm and __switch_to_xtra, and
__switch_to_xtra is called shortly after switch_mm during context
switch, so the cacheline is likely to be hot.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Vince Weaver <vince@deater.net>
Cc: "hillf.zj" <hillf.zj@alibaba-inc.com>
Cc: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/3a54dd3353fffbf84804398e00dfdc5b7c1afd7d.1414190806.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Andy Lutomirski 2014-10-24 15:58:08 -07:00 committed by Ingo Molnar
parent 375074cc73
commit 1e02ce4ccc
20 changed files with 85 additions and 46 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/x86/include/asm/paravirt.h
View File

@ -80,16 +80,16 @@ static inline void write_cr3(unsigned long x)
PVOP_VCALL1(pv_mmu_ops.write_cr3, x);
}
static inline unsigned long read_cr4(void)
static inline unsigned long __read_cr4(void)
{
return PVOP_CALL0(unsigned long, pv_cpu_ops.read_cr4);
}
static inline unsigned long read_cr4_safe(void)
static inline unsigned long __read_cr4_safe(void)
{
return PVOP_CALL0(unsigned long, pv_cpu_ops.read_cr4_safe);
}
static inline void write_cr4(unsigned long x)
static inline void __write_cr4(unsigned long x)
{
PVOP_VCALL1(pv_cpu_ops.write_cr4, x);
}

6
arch/x86/include/asm/special_insns.h
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@ -137,17 +137,17 @@ static inline void write_cr3(unsigned long x)
native_write_cr3(x);
}
static inline unsigned long read_cr4(void)
static inline unsigned long __read_cr4(void)
{
return native_read_cr4();
}
static inline unsigned long read_cr4_safe(void)
static inline unsigned long __read_cr4_safe(void)
{
return native_read_cr4_safe();
}
static inline void write_cr4(unsigned long x)
static inline void __write_cr4(unsigned long x)
{
native_write_cr4(x);
}

52
arch/x86/include/asm/tlbflush.h
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@ -15,14 +15,37 @@
#define __flush_tlb_single(addr) __native_flush_tlb_single(addr)
#endif
struct tlb_state {
#ifdef CONFIG_SMP
struct mm_struct *active_mm;
int state;
#endif
/*
* Access to this CR4 shadow and to H/W CR4 is protected by
* disabling interrupts when modifying either one.
*/
unsigned long cr4;
};
DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate);
/* Initialize cr4 shadow for this CPU. */
static inline void cr4_init_shadow(void)
{
this_cpu_write(cpu_tlbstate.cr4, __read_cr4());
}
/* Set in this cpu's CR4. */
static inline void cr4_set_bits(unsigned long mask)
{
unsigned long cr4;
cr4 = read_cr4();
cr4 |= mask;
write_cr4(cr4);
cr4 = this_cpu_read(cpu_tlbstate.cr4);
if ((cr4 | mask) != cr4) {
cr4 |= mask;
this_cpu_write(cpu_tlbstate.cr4, cr4);
__write_cr4(cr4);
}
}
/* Clear in this cpu's CR4. */
@ -30,9 +53,18 @@ static inline void cr4_clear_bits(unsigned long mask)
{
unsigned long cr4;
cr4 = read_cr4();
cr4 &= ~mask;
write_cr4(cr4);
cr4 = this_cpu_read(cpu_tlbstate.cr4);
if ((cr4 & ~mask) != cr4) {
cr4 &= ~mask;
this_cpu_write(cpu_tlbstate.cr4, cr4);
__write_cr4(cr4);
}
}
/* Read the CR4 shadow. */
static inline unsigned long cr4_read_shadow(void)
{
return this_cpu_read(cpu_tlbstate.cr4);
}
/*
@ -61,7 +93,7 @@ static inline void __native_flush_tlb_global_irq_disabled(void)
{
unsigned long cr4;
cr4 = native_read_cr4();
cr4 = this_cpu_read(cpu_tlbstate.cr4);
/* clear PGE */
native_write_cr4(cr4 & ~X86_CR4_PGE);
/* write old PGE again and flush TLBs */
@ -221,12 +253,6 @@ void native_flush_tlb_others(const struct cpumask *cpumask,
#define TLBSTATE_OK 1
#define TLBSTATE_LAZY 2
struct tlb_state {
struct mm_struct *active_mm;
int state;
};
DECLARE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate);
static inline void reset_lazy_tlbstate(void)
{
this_cpu_write(cpu_tlbstate.state, 0);

2
arch/x86/include/asm/virtext.h
View File

@ -46,7 +46,7 @@ static inline void cpu_vmxoff(void)
static inline int cpu_vmx_enabled(void)
{
return read_cr4() & X86_CR4_VMXE;
return __read_cr4() & X86_CR4_VMXE;
}
/** Disable VMX if it is enabled on the current CPU

2
arch/x86/kernel/acpi/sleep.c
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@ -78,7 +78,7 @@ int x86_acpi_suspend_lowlevel(void)
header->pmode_cr0 = read_cr0();
if (__this_cpu_read(cpu_info.cpuid_level) >= 0) {
header->pmode_cr4 = read_cr4();
header->pmode_cr4 = __read_cr4();
header->pmode_behavior |= (1 << WAKEUP_BEHAVIOR_RESTORE_CR4);
}
if (!rdmsr_safe(MSR_IA32_MISC_ENABLE,

7
arch/x86/kernel/cpu/common.c
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@ -19,6 +19,7 @@
#include <asm/archrandom.h>
#include <asm/hypervisor.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/debugreg.h>
#include <asm/sections.h>
#include <asm/vsyscall.h>
@ -1293,6 +1294,12 @@ void cpu_init(void)
wait_for_master_cpu(cpu);
/*
* Initialize the CR4 shadow before doing anything that could
* try to read it.
*/
cr4_init_shadow();
/*
* Load microcode on this cpu if a valid microcode is available.
* This is early microcode loading procedure.

6
arch/x86/kernel/cpu/mtrr/cyrix.c
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@ -138,8 +138,8 @@ static void prepare_set(void)
/* Save value of CR4 and clear Page Global Enable (bit 7) */
if (cpu_has_pge) {
cr4 = read_cr4();
write_cr4(cr4 & ~X86_CR4_PGE);
cr4 = __read_cr4();
__write_cr4(cr4 & ~X86_CR4_PGE);
}
/*
@ -171,7 +171,7 @@ static void post_set(void)
/* Restore value of CR4 */
if (cpu_has_pge)
write_cr4(cr4);
__write_cr4(cr4);
}
static void cyrix_set_arr(unsigned int reg, unsigned long base,

6
arch/x86/kernel/cpu/mtrr/generic.c
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@ -678,8 +678,8 @@ static void prepare_set(void) __acquires(set_atomicity_lock)
/* Save value of CR4 and clear Page Global Enable (bit 7) */
if (cpu_has_pge) {
cr4 = read_cr4();
write_cr4(cr4 & ~X86_CR4_PGE);
cr4 = __read_cr4();
__write_cr4(cr4 & ~X86_CR4_PGE);
}
/* Flush all TLBs via a mov %cr3, %reg; mov %reg, %cr3 */
@ -708,7 +708,7 @@ static void post_set(void) __releases(set_atomicity_lock)
/* Restore value of CR4 */
if (cpu_has_pge)
write_cr4(cr4);
__write_cr4(cr4);
raw_spin_unlock(&set_atomicity_lock);
}

1
arch/x86/kernel/head32.c
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@ -31,6 +31,7 @@ static void __init i386_default_early_setup(void)
asmlinkage __visible void __init i386_start_kernel(void)
{
cr4_init_shadow();
sanitize_boot_params(&boot_params);
/* Call the subarch specific early setup function */

2
arch/x86/kernel/head64.c
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@ -155,6 +155,8 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
(__START_KERNEL & PGDIR_MASK)));
BUILD_BUG_ON(__fix_to_virt(__end_of_fixed_addresses) <= MODULES_END);
cr4_init_shadow();
/* Kill off the identity-map trampoline */
reset_early_page_tables();

2
arch/x86/kernel/process_32.c
View File

@ -101,7 +101,7 @@ void __show_regs(struct pt_regs *regs, int all)
cr0 = read_cr0();
cr2 = read_cr2();
cr3 = read_cr3();
cr4 = read_cr4_safe();
cr4 = __read_cr4_safe();
printk(KERN_DEFAULT "CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n",
cr0, cr2, cr3, cr4);

2
arch/x86/kernel/process_64.c
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@ -93,7 +93,7 @@ void __show_regs(struct pt_regs *regs, int all)
cr0 = read_cr0();
cr2 = read_cr2();
cr3 = read_cr3();
cr4 = read_cr4();
cr4 = __read_cr4();
printk(KERN_DEFAULT "FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n",
fs, fsindex, gs, gsindex, shadowgs);

2
arch/x86/kernel/setup.c
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@ -1178,7 +1178,7 @@ void __init setup_arch(char **cmdline_p)
if (boot_cpu_data.cpuid_level >= 0) {
/* A CPU has %cr4 if and only if it has CPUID */
mmu_cr4_features = read_cr4();
mmu_cr4_features = __read_cr4();
if (trampoline_cr4_features)
*trampoline_cr4_features = mmu_cr4_features;
}

2
arch/x86/kvm/svm.c
View File

@ -1583,7 +1583,7 @@ static void svm_set_cr0(struct kvm_vcpu *vcpu, unsigned long cr0)
static int svm_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
{
unsigned long host_cr4_mce = read_cr4() & X86_CR4_MCE;
unsigned long host_cr4_mce = cr4_read_shadow() & X86_CR4_MCE;
unsigned long old_cr4 = to_svm(vcpu)->vmcb->save.cr4;
if (cr4 & X86_CR4_VMXE)

6
arch/x86/kvm/vmx.c
View File

@ -2785,7 +2785,7 @@ static int hardware_enable(void)
u64 phys_addr = __pa(per_cpu(vmxarea, cpu));
u64 old, test_bits;
if (read_cr4() & X86_CR4_VMXE)
if (cr4_read_shadow() & X86_CR4_VMXE)
return -EBUSY;
INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
@ -4255,7 +4255,7 @@ static void vmx_set_constant_host_state(struct vcpu_vmx *vmx)
vmcs_writel(HOST_CR3, read_cr3()); /* 22.2.3 FIXME: shadow tables */
/* Save the most likely value for this task's CR4 in the VMCS. */
cr4 = read_cr4();
cr4 = cr4_read_shadow();
vmcs_writel(HOST_CR4, cr4); /* 22.2.3, 22.2.5 */
vmx->host_state.vmcs_host_cr4 = cr4;
@ -7784,7 +7784,7 @@ static void __noclone vmx_vcpu_run(struct kvm_vcpu *vcpu)
if (test_bit(VCPU_REGS_RIP, (unsigned long *)&vcpu->arch.regs_dirty))
vmcs_writel(GUEST_RIP, vcpu->arch.regs[VCPU_REGS_RIP]);
cr4 = read_cr4();
cr4 = cr4_read_shadow();
if (unlikely(cr4 != vmx->host_state.vmcs_host_cr4)) {
vmcs_writel(HOST_CR4, cr4);
vmx->host_state.vmcs_host_cr4 = cr4;

2
arch/x86/mm/fault.c
View File

@ -600,7 +600,7 @@ show_fault_oops(struct pt_regs *regs, unsigned long error_code,
printk(nx_warning, from_kuid(&init_user_ns, current_uid()));
if (pte && pte_present(*pte) && pte_exec(*pte) &&
(pgd_flags(*pgd) & _PAGE_USER) &&
(read_cr4() & X86_CR4_SMEP))
(__read_cr4() & X86_CR4_SMEP))
printk(smep_warning, from_kuid(&init_user_ns, current_uid()));
}

9
arch/x86/mm/init.c
View File

@ -713,6 +713,15 @@ void __init zone_sizes_init(void)
free_area_init_nodes(max_zone_pfns);
}
DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate) = {
#ifdef CONFIG_SMP
.active_mm = &init_mm,
.state = 0,
#endif
.cr4 = ~0UL, /* fail hard if we screw up cr4 shadow initialization */
};
EXPORT_SYMBOL_GPL(cpu_tlbstate);
void update_cache_mode_entry(unsigned entry, enum page_cache_mode cache)
{
/* entry 0 MUST be WB (hardwired to speed up translations) */

3
arch/x86/mm/tlb.c
View File

@ -14,9 +14,6 @@
#include <asm/uv/uv.h>
#include <linux/debugfs.h>
DEFINE_PER_CPU_SHARED_ALIGNED(struct tlb_state, cpu_tlbstate)
= { &init_mm, 0, };
/*
* Smarter SMP flushing macros.
* c/o Linus Torvalds.

11
arch/x86/power/cpu.c
View File

@ -105,11 +105,8 @@ static void __save_processor_state(struct saved_context *ctxt)
ctxt->cr0 = read_cr0();
ctxt->cr2 = read_cr2();
ctxt->cr3 = read_cr3();
#ifdef CONFIG_X86_32
ctxt->cr4 = read_cr4_safe();
#else
/* CONFIG_X86_64 */
ctxt->cr4 = read_cr4();
ctxt->cr4 = __read_cr4_safe();
#ifdef CONFIG_X86_64
ctxt->cr8 = read_cr8();
#endif
ctxt->misc_enable_saved = !rdmsrl_safe(MSR_IA32_MISC_ENABLE,
@ -175,12 +172,12 @@ static void notrace __restore_processor_state(struct saved_context *ctxt)
/* cr4 was introduced in the Pentium CPU */
#ifdef CONFIG_X86_32
if (ctxt->cr4)
write_cr4(ctxt->cr4);
__write_cr4(ctxt->cr4);
#else
/* CONFIG X86_64 */
wrmsrl(MSR_EFER, ctxt->efer);
write_cr8(ctxt->cr8);
write_cr4(ctxt->cr4);
__write_cr4(ctxt->cr4);
#endif
write_cr3(ctxt->cr3);
write_cr2(ctxt->cr2);

2
arch/x86/realmode/init.c
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@ -81,7 +81,7 @@ void __init setup_real_mode(void)
trampoline_header->start = (u64) secondary_startup_64;
trampoline_cr4_features = &trampoline_header->cr4;
*trampoline_cr4_features = read_cr4();
*trampoline_cr4_features = __read_cr4();
trampoline_pgd = (u64 *) __va(real_mode_header->trampoline_pgd);
trampoline_pgd[0] = init_level4_pgt[pgd_index(__PAGE_OFFSET)].pgd;