diff options
| author | Alexey Kardashevskiy <aik@amd.com> | 2023-01-20 06:10:45 +0300 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-01-31 22:09:26 +0300 |
| commit | 7914695743d598b189d549f2f57af24aa5633705 (patch) | |
| tree | 801a28c227627f0d97a408d65a0f195fa2648137 /arch/x86/include/asm/debugreg.h | |
| parent | 8c19b6f257fa71ed3a7a9df6ce466c6be31ca04c (diff) | |
| download | linux-7914695743d598b189d549f2f57af24aa5633705.tar.xz | |
x86/amd: Cache debug register values in percpu variables
Reading DR[0-3]_ADDR_MASK MSRs takes about 250 cycles which is going to
be noticeable with the AMD KVM SEV-ES DebugSwap feature enabled. KVM is
going to store host's DR[0-3] and DR[0-3]_ADDR_MASK before switching to
a guest; the hardware is going to swap these on VMRUN and VMEXIT.
Store MSR values passed to set_dr_addr_mask() in percpu variables
(when changed) and return them via new amd_get_dr_addr_mask().
The gain here is about 10x.
As set_dr_addr_mask() uses the array too, change the @dr type to
unsigned to avoid checking for <0. And give it the amd_ prefix to match
the new helper as the whole DR_ADDR_MASK feature is AMD-specific anyway.
While at it, replace deprecated boot_cpu_has() with cpu_feature_enabled()
in set_dr_addr_mask().
Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230120031047.628097-2-aik@amd.com
Diffstat (limited to 'arch/x86/include/asm/debugreg.h')
| -rw-r--r-- | arch/x86/include/asm/debugreg.h | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index b049d950612f..f126b2ee890f 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -126,9 +126,14 @@ static __always_inline void local_db_restore(unsigned long dr7) } #ifdef CONFIG_CPU_SUP_AMD -extern void set_dr_addr_mask(unsigned long mask, int dr); +extern void amd_set_dr_addr_mask(unsigned long mask, unsigned int dr); +extern unsigned long amd_get_dr_addr_mask(unsigned int dr); #else -static inline void set_dr_addr_mask(unsigned long mask, int dr) { } +static inline void amd_set_dr_addr_mask(unsigned long mask, unsigned int dr) { } +static inline unsigned long amd_get_dr_addr_mask(unsigned int dr) +{ + return 0; +} #endif #endif /* _ASM_X86_DEBUGREG_H */ |