From: Mark Rutland <mark.rutland@xxxxxxx> We finalize caps before initializing kvm hyp code, and any use of cpus_have_const_cap() in kvm hyp code generates redundant and potentially unsound code to read the cpu_hwcaps array. A number of helper functions used in both hyp context and regular kernel context use cpus_have_const_cap(), as some regular kernel code runs before the capabilities are finalized. It's tedious and error-prone to write separate copies of these for hyp and non-hyp code. So that we can avoid the redundant code, let's automatically upgrade cpus_have_const_cap() to cpus_have_final_cap() when used in hyp context. With this change, there's never a reason to access to cpu_hwcaps array from hyp code, and we don't need to create an NVHE alias for this. This should have no effect on non-hyp code. Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> Acked-by: Will Deacon <will@xxxxxxxxxx> Cc: David Brazdil <dbrazdil@xxxxxxxxxx> Cc: Marc Zyngier <maz@xxxxxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Link: https://lore.kernel.org/r/20201026134931.28246-4-mark.rutland@xxxxxxx --- arch/arm64/include/asm/cpufeature.h | 26 ++++++++++++++++++++++++-- arch/arm64/include/asm/virt.h | 12 ------------ arch/arm64/kernel/image-vars.h | 1 - 3 files changed, 24 insertions(+), 15 deletions(-) diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h index 9f671aa0419b..79d6a0371c78 100644 --- a/arch/arm64/include/asm/cpufeature.h +++ b/arch/arm64/include/asm/cpufeature.h @@ -375,6 +375,23 @@ cpucap_multi_entry_cap_matches(const struct arm64_cpu_capabilities *entry, return false; } +static __always_inline bool is_vhe_hyp_code(void) +{ + /* Only defined for code run in VHE hyp context */ + return __is_defined(__KVM_VHE_HYPERVISOR__); +} + +static __always_inline bool is_nvhe_hyp_code(void) +{ + /* Only defined for code run in NVHE hyp context */ + return __is_defined(__KVM_NVHE_HYPERVISOR__); +} + +static __always_inline bool is_hyp_code(void) +{ + return is_vhe_hyp_code() || is_nvhe_hyp_code(); +} + extern DECLARE_BITMAP(cpu_hwcaps, ARM64_NCAPS); extern struct static_key_false cpu_hwcap_keys[ARM64_NCAPS]; extern struct static_key_false arm64_const_caps_ready; @@ -444,8 +461,11 @@ static __always_inline bool cpus_have_final_cap(int num) } /* - * Test for a capability, possibly with a runtime check. + * Test for a capability, possibly with a runtime check for non-hyp code. * + * For hyp code, this behaves the same as cpus_have_final_cap(). + * + * For non-hyp code: * Before capabilities are finalized, this behaves as cpus_have_cap(). * After capabilities are finalized, this is patched to avoid a runtime check. * @@ -453,7 +473,9 @@ static __always_inline bool cpus_have_final_cap(int num) */ static __always_inline bool cpus_have_const_cap(int num) { - if (system_capabilities_finalized()) + if (is_hyp_code()) + return cpus_have_final_cap(num); + else if (system_capabilities_finalized()) return __cpus_have_const_cap(num); else return cpus_have_cap(num); diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index 300be14ba77b..6069be50baf9 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -83,18 +83,6 @@ static inline bool is_kernel_in_hyp_mode(void) return read_sysreg(CurrentEL) == CurrentEL_EL2; } -static __always_inline bool is_vhe_hyp_code(void) -{ - /* Only defined for code run in VHE hyp context */ - return __is_defined(__KVM_VHE_HYPERVISOR__); -} - -static __always_inline bool is_nvhe_hyp_code(void) -{ - /* Only defined for code run in NVHE hyp context */ - return __is_defined(__KVM_NVHE_HYPERVISOR__); -} - static __always_inline bool has_vhe(void) { /* diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h index fbd4b6b1fde5..ad8432251733 100644 --- a/arch/arm64/kernel/image-vars.h +++ b/arch/arm64/kernel/image-vars.h @@ -87,7 +87,6 @@ KVM_NVHE_ALIAS(__icache_flags); /* Kernel symbols needed for cpus_have_final/const_caps checks. */ KVM_NVHE_ALIAS(arm64_const_caps_ready); KVM_NVHE_ALIAS(cpu_hwcap_keys); -KVM_NVHE_ALIAS(cpu_hwcaps); /* Static keys which are set if a vGIC trap should be handled in hyp. */ KVM_NVHE_ALIAS(vgic_v2_cpuif_trap); -- 2.28.0
