diff options
Diffstat (limited to 'arch/x86/kernel/fpu')
| -rw-r--r-- | arch/x86/kernel/fpu/core.c | 53 | ||||
| -rw-r--r-- | arch/x86/kernel/fpu/init.c | 1 | ||||
| -rw-r--r-- | arch/x86/kernel/fpu/xstate.c | 40 |
3 files changed, 73 insertions, 21 deletions
diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index ea138583dd92..aefd412a23dc 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -37,6 +37,7 @@ DEFINE_PER_CPU(u64, xfd_state); /* The FPU state configuration data for kernel and user space */ struct fpu_state_config fpu_kernel_cfg __ro_after_init; struct fpu_state_config fpu_user_cfg __ro_after_init; +struct vcpu_fpu_config guest_default_cfg __ro_after_init; /* * Represents the initial FPU state. It's mostly (but not completely) zeroes, @@ -217,7 +218,7 @@ void fpu_reset_from_exception_fixup(void) } #if IS_ENABLED(CONFIG_KVM) -static void __fpstate_reset(struct fpstate *fpstate, u64 xfd); +static void __fpstate_reset(struct fpstate *fpstate); static void fpu_lock_guest_permissions(void) { @@ -242,19 +243,21 @@ bool fpu_alloc_guest_fpstate(struct fpu_guest *gfpu) struct fpstate *fpstate; unsigned int size; - size = fpu_kernel_cfg.default_size + ALIGN(offsetof(struct fpstate, regs), 64); + size = guest_default_cfg.size + ALIGN(offsetof(struct fpstate, regs), 64); + fpstate = vzalloc(size); if (!fpstate) return false; - /* Leave xfd to 0 (the reset value defined by spec) */ - __fpstate_reset(fpstate, 0); - fpstate_init_user(fpstate); + /* Initialize indicators to reflect properties of the fpstate */ fpstate->is_valloc = true; fpstate->is_guest = true; + __fpstate_reset(fpstate); + fpstate_init_user(fpstate); + gfpu->fpstate = fpstate; - gfpu->xfeatures = fpu_kernel_cfg.default_features; + gfpu->xfeatures = guest_default_cfg.features; /* * KVM sets the FP+SSE bits in the XSAVE header when copying FPU state @@ -541,28 +544,50 @@ void fpstate_init_user(struct fpstate *fpstate) fpstate_init_fstate(fpstate); } -static void __fpstate_reset(struct fpstate *fpstate, u64 xfd) +static void __fpstate_reset(struct fpstate *fpstate) { - /* Initialize sizes and feature masks */ - fpstate->size = fpu_kernel_cfg.default_size; + /* + * Supervisor features (and thus sizes) may diverge between guest + * FPUs and host FPUs, as some supervisor features are supported + * for guests despite not being utilized by the host. User + * features and sizes are always identical, which allows for + * common guest and userspace ABI. + * + * For the host, set XFD to the kernel's desired initialization + * value. For guests, set XFD to its architectural RESET value. + */ + if (fpstate->is_guest) { + fpstate->size = guest_default_cfg.size; + fpstate->xfeatures = guest_default_cfg.features; + fpstate->xfd = 0; + } else { + fpstate->size = fpu_kernel_cfg.default_size; + fpstate->xfeatures = fpu_kernel_cfg.default_features; + fpstate->xfd = init_fpstate.xfd; + } + fpstate->user_size = fpu_user_cfg.default_size; - fpstate->xfeatures = fpu_kernel_cfg.default_features; fpstate->user_xfeatures = fpu_user_cfg.default_features; - fpstate->xfd = xfd; } void fpstate_reset(struct fpu *fpu) { /* Set the fpstate pointer to the default fpstate */ fpu->fpstate = &fpu->__fpstate; - __fpstate_reset(fpu->fpstate, init_fpstate.xfd); + __fpstate_reset(fpu->fpstate); /* Initialize the permission related info in fpu */ fpu->perm.__state_perm = fpu_kernel_cfg.default_features; fpu->perm.__state_size = fpu_kernel_cfg.default_size; fpu->perm.__user_state_size = fpu_user_cfg.default_size; - /* Same defaults for guests */ - fpu->guest_perm = fpu->perm; + + fpu->guest_perm.__state_perm = guest_default_cfg.features; + fpu->guest_perm.__state_size = guest_default_cfg.size; + /* + * User features and sizes are always identical between host and + * guest FPUs, which allows for common guest and userspace ABI. + */ + fpu->guest_perm.__user_state_size = fpu_user_cfg.default_size; } static inline void fpu_inherit_perms(struct fpu *dst_fpu) diff --git a/arch/x86/kernel/fpu/init.c b/arch/x86/kernel/fpu/init.c index 99db41bf9fa6..ff988b9ea39f 100644 --- a/arch/x86/kernel/fpu/init.c +++ b/arch/x86/kernel/fpu/init.c @@ -205,6 +205,7 @@ static void __init fpu__init_system_xstate_size_legacy(void) fpu_kernel_cfg.default_size = size; fpu_user_cfg.max_size = size; fpu_user_cfg.default_size = size; + guest_default_cfg.size = size; } /* diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 9aa9ac8399ae..12ed75c1b567 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -57,7 +57,7 @@ static const char *xfeature_names[] = "Protection Keys User registers", "PASID state", "Control-flow User registers", - "Control-flow Kernel registers (unused)", + "Control-flow Kernel registers (KVM only)", "unknown xstate feature", "unknown xstate feature", "unknown xstate feature", @@ -81,6 +81,7 @@ static unsigned short xsave_cpuid_features[] __initdata = { [XFEATURE_PKRU] = X86_FEATURE_OSPKE, [XFEATURE_PASID] = X86_FEATURE_ENQCMD, [XFEATURE_CET_USER] = X86_FEATURE_SHSTK, + [XFEATURE_CET_KERNEL] = X86_FEATURE_SHSTK, [XFEATURE_XTILE_CFG] = X86_FEATURE_AMX_TILE, [XFEATURE_XTILE_DATA] = X86_FEATURE_AMX_TILE, [XFEATURE_APX] = X86_FEATURE_APX, @@ -372,6 +373,7 @@ static __init void os_xrstor_booting(struct xregs_state *xstate) XFEATURE_MASK_BNDCSR | \ XFEATURE_MASK_PASID | \ XFEATURE_MASK_CET_USER | \ + XFEATURE_MASK_CET_KERNEL | \ XFEATURE_MASK_XTILE | \ XFEATURE_MASK_APX) @@ -573,6 +575,7 @@ static bool __init check_xstate_against_struct(int nr) case XFEATURE_PASID: return XCHECK_SZ(sz, nr, struct ia32_pasid_state); case XFEATURE_XTILE_CFG: return XCHECK_SZ(sz, nr, struct xtile_cfg); case XFEATURE_CET_USER: return XCHECK_SZ(sz, nr, struct cet_user_state); + case XFEATURE_CET_KERNEL: return XCHECK_SZ(sz, nr, struct cet_supervisor_state); case XFEATURE_APX: return XCHECK_SZ(sz, nr, struct apx_state); case XFEATURE_XTILE_DATA: check_xtile_data_against_struct(sz); return true; default: @@ -743,6 +746,9 @@ static int __init init_xstate_size(void) fpu_user_cfg.default_size = xstate_calculate_size(fpu_user_cfg.default_features, false); + guest_default_cfg.size = + xstate_calculate_size(guest_default_cfg.features, compacted); + return 0; } @@ -763,6 +769,7 @@ static void __init fpu__init_disable_system_xstate(unsigned int legacy_size) fpu_kernel_cfg.default_size = legacy_size; fpu_user_cfg.max_size = legacy_size; fpu_user_cfg.default_size = legacy_size; + guest_default_cfg.size = legacy_size; /* * Prevent enabling the static branch which enables writes to the @@ -773,6 +780,24 @@ static void __init fpu__init_disable_system_xstate(unsigned int legacy_size) fpstate_reset(x86_task_fpu(current)); } +static u64 __init host_default_mask(void) +{ + /* + * Exclude dynamic features (require userspace opt-in) and features + * that are supported only for KVM guests. + */ + return ~((u64)XFEATURE_MASK_USER_DYNAMIC | XFEATURE_MASK_GUEST_SUPERVISOR); +} + +static u64 __init guest_default_mask(void) +{ + /* + * Exclude dynamic features, which require userspace opt-in even + * for KVM guests. + */ + return ~(u64)XFEATURE_MASK_USER_DYNAMIC; +} + /* * Enable and initialize the xsave feature. * Called once per system bootup. @@ -855,12 +880,13 @@ void __init fpu__init_system_xstate(unsigned int legacy_size) fpu_user_cfg.max_features = fpu_kernel_cfg.max_features; fpu_user_cfg.max_features &= XFEATURE_MASK_USER_SUPPORTED; - /* Clean out dynamic features from default */ - fpu_kernel_cfg.default_features = fpu_kernel_cfg.max_features; - fpu_kernel_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC; - - fpu_user_cfg.default_features = fpu_user_cfg.max_features; - fpu_user_cfg.default_features &= ~XFEATURE_MASK_USER_DYNAMIC; + /* + * Now, given maximum feature set, determine default values by + * applying default masks. + */ + fpu_kernel_cfg.default_features = fpu_kernel_cfg.max_features & host_default_mask(); + fpu_user_cfg.default_features = fpu_user_cfg.max_features & host_default_mask(); + guest_default_cfg.features = fpu_kernel_cfg.max_features & guest_default_mask(); /* Store it for paranoia check at the end */ xfeatures = fpu_kernel_cfg.max_features; |