kernel-ark/arch/x86
Avi Kivity 97d64b7881 KVM: MMU: Optimize pte permission checks
walk_addr_generic() permission checks are a maze of branchy code, which is
performed four times per lookup.  It depends on the type of access, efer.nxe,
cr0.wp, cr4.smep, and in the near future, cr4.smap.

Optimize this away by precalculating all variants and storing them in a
bitmap.  The bitmap is recalculated when rarely-changing variables change
(cr0, cr4) and is indexed by the often-changing variables (page fault error
code, pte access permissions).

The permission check is moved to the end of the loop, otherwise an SMEP
fault could be reported as a false positive, when PDE.U=1 but PTE.U=0.
Noted by Xiao Guangrong.

The result is short, branch-free code.

Reviewed-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
2012-09-20 13:00:08 +03:00
..
boot x86, build: Globally set -fno-pic 2012-08-10 16:12:30 -07:00
configs x86/kconfig: Remove CONFIG_TR=y from the defconfigs 2012-03-24 08:18:03 +01:00
crypto crypto: twofish-avx - remove useless instruction 2012-07-11 11:08:30 +08:00
ia32 x86, compat: Use test_thread_flag(TIF_IA32) in compat signal delivery 2012-06-14 18:16:04 -07:00
include/asm KVM: MMU: Optimize pte permission checks 2012-09-20 13:00:08 +03:00
kernel Merge remote-tracking branch 'upstream/master' into queue 2012-08-26 13:58:41 -03:00
kvm KVM: MMU: Optimize pte permission checks 2012-09-20 13:00:08 +03:00
lguest
lib Merge branch 'x86/cpu' into perf/core 2012-07-05 21:12:11 +02:00
math-emu x86: Rename trap_no to trap_nr in thread_struct 2012-03-13 06:24:09 +01:00
mm mm: hugetlbfs: correctly populate shared pmd 2012-08-21 16:45:02 -07:00
net x86 bpf_jit: support BPF_S_ANC_ALU_XOR_X instruction 2012-06-06 09:42:44 -07:00
oprofile perf/x86/amd: Unify AMD's generic and family 15h pmus 2012-07-05 21:19:41 +02:00
pci Merge branch 'pci/myron-pcibios_setup' into next 2012-07-05 15:31:05 -06:00
platform Revert "x86-64/efi: Use EFI to deal with platform wall clock" 2012-08-14 09:58:25 -07:00
power x86, kvm: Call restore_sched_clock_state() only after %gs is initialized 2012-04-02 13:53:00 +02:00
realmode x86, build: Globally set -fno-pic 2012-08-10 16:12:30 -07:00
syscalls x32: Use compat shims for {g,s}etsockopt 2012-08-18 14:15:39 -07:00
tools x86/decoder: Fix bsr/bsf/jmpe decoding with operand-size prefix 2012-06-06 08:54:18 +02:00
um um: switch UPT_SET_RETURN_VALUE and regs_return_value to pt_regs 2012-08-01 23:33:16 +02:00
vdso x86, cpu: Rename checking_wrmsrl() to wrmsrl_safe() 2012-06-07 13:32:04 -07:00
video x86: Use vga_default_device() when determining whether an fb is primary 2012-04-24 09:50:17 +01:00
xen Three bug-fixes: 2012-08-25 17:31:59 -07:00
.gitignore
Kbuild x86, realmode: realmode.bin infrastructure 2012-05-08 11:41:48 -07:00
Kconfig x86: KVM guest: merge CONFIG_KVM_CLOCK into CONFIG_KVM_GUEST 2012-08-23 04:57:54 -03:00
Kconfig.cpu
Kconfig.debug x86/tlb: add tlb_flushall_shift knob into debugfs 2012-06-27 19:29:10 -07:00
Makefile x86, build: Globally set -fno-pic 2012-08-10 16:12:30 -07:00
Makefile_32.cpu
Makefile.um um: fix linker script generation 2012-04-09 13:59:00 -04:00