diff options
| -rw-r--r-- | arch/x86/include/asm/fpu/types.h | 7 | ||||
| -rw-r--r-- | arch/x86/include/asm/fpu/xstate.h | 30 | ||||
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 15 |
3 files changed, 47 insertions, 5 deletions
diff --git a/arch/x86/include/asm/fpu/types.h b/arch/x86/include/asm/fpu/types.h index f098f6cab94b..132e9cc26d60 100644 --- a/arch/x86/include/asm/fpu/types.h +++ b/arch/x86/include/asm/fpu/types.h @@ -114,6 +114,12 @@ enum xfeature { XFEATURE_Hi16_ZMM, XFEATURE_PT_UNIMPLEMENTED_SO_FAR, XFEATURE_PKRU, + XFEATURE_RSRVD_COMP_10, + XFEATURE_RSRVD_COMP_11, + XFEATURE_RSRVD_COMP_12, + XFEATURE_RSRVD_COMP_13, + XFEATURE_RSRVD_COMP_14, + XFEATURE_LBR, XFEATURE_MAX, }; @@ -128,6 +134,7 @@ enum xfeature { #define XFEATURE_MASK_Hi16_ZMM (1 << XFEATURE_Hi16_ZMM) #define XFEATURE_MASK_PT (1 << XFEATURE_PT_UNIMPLEMENTED_SO_FAR) #define XFEATURE_MASK_PKRU (1 << XFEATURE_PKRU) +#define XFEATURE_MASK_LBR (1 << XFEATURE_LBR) #define XFEATURE_MASK_FPSSE (XFEATURE_MASK_FP | XFEATURE_MASK_SSE) #define XFEATURE_MASK_AVX512 (XFEATURE_MASK_OPMASK \ diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index 422d8369012a..040c4d49bfcb 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -36,6 +36,27 @@ #define XFEATURE_MASK_SUPERVISOR_SUPPORTED (0) /* + * A supervisor state component may not always contain valuable information, + * and its size may be huge. Saving/restoring such supervisor state components + * at each context switch can cause high CPU and space overhead, which should + * be avoided. Such supervisor state components should only be saved/restored + * on demand. The on-demand dynamic supervisor features are set in this mask. + * + * Unlike the existing supported supervisor features, a dynamic supervisor + * feature does not allocate a buffer in task->fpu, and the corresponding + * supervisor state component cannot be saved/restored at each context switch. + * + * To support a dynamic supervisor feature, a developer should follow the + * dos and don'ts as below: + * - Do dynamically allocate a buffer for the supervisor state component. + * - Do manually invoke the XSAVES/XRSTORS instruction to save/restore the + * state component to/from the buffer. + * - Don't set the bit corresponding to the dynamic supervisor feature in + * IA32_XSS at run time, since it has been set at boot time. + */ +#define XFEATURE_MASK_DYNAMIC (XFEATURE_MASK_LBR) + +/* * Unsupported supervisor features. When a supervisor feature in this mask is * supported in the future, move it to the supported supervisor feature mask. */ @@ -43,6 +64,7 @@ /* All supervisor states including supported and unsupported states. */ #define XFEATURE_MASK_SUPERVISOR_ALL (XFEATURE_MASK_SUPERVISOR_SUPPORTED | \ + XFEATURE_MASK_DYNAMIC | \ XFEATURE_MASK_SUPERVISOR_UNSUPPORTED) #ifdef CONFIG_X86_64 @@ -63,6 +85,14 @@ static inline u64 xfeatures_mask_user(void) return xfeatures_mask_all & XFEATURE_MASK_USER_SUPPORTED; } +static inline u64 xfeatures_mask_dynamic(void) +{ + if (!boot_cpu_has(X86_FEATURE_ARCH_LBR)) + return XFEATURE_MASK_DYNAMIC & ~XFEATURE_MASK_LBR; + + return XFEATURE_MASK_DYNAMIC; +} + extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS]; extern void __init update_regset_xstate_info(unsigned int size, diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index bda2e5eaca0e..dcf062442b18 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -233,8 +233,10 @@ void fpu__init_cpu_xstate(void) /* * MSR_IA32_XSS sets supervisor states managed by XSAVES. */ - if (boot_cpu_has(X86_FEATURE_XSAVES)) - wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()); + if (boot_cpu_has(X86_FEATURE_XSAVES)) { + wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() | + xfeatures_mask_dynamic()); + } } static bool xfeature_enabled(enum xfeature xfeature) @@ -598,7 +600,8 @@ static void check_xstate_against_struct(int nr) */ if ((nr < XFEATURE_YMM) || (nr >= XFEATURE_MAX) || - (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR)) { + (nr == XFEATURE_PT_UNIMPLEMENTED_SO_FAR) || + ((nr >= XFEATURE_RSRVD_COMP_10) && (nr <= XFEATURE_LBR))) { WARN_ONCE(1, "no structure for xstate: %d\n", nr); XSTATE_WARN_ON(1); } @@ -847,8 +850,10 @@ void fpu__resume_cpu(void) * Restore IA32_XSS. The same CPUID bit enumerates support * of XSAVES and MSR_IA32_XSS. */ - if (boot_cpu_has(X86_FEATURE_XSAVES)) - wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor()); + if (boot_cpu_has(X86_FEATURE_XSAVES)) { + wrmsrl(MSR_IA32_XSS, xfeatures_mask_supervisor() | + xfeatures_mask_dynamic()); + } } /* |