From: Mark Rutland <mark.rutland@xxxxxxx> commit 8eca7f6d5100b6997df4f532090bc3f7e0203bef upstream. Now that the host eagerly saves its own FPSIMD/SVE/SME state, non-protected KVM never needs to save the host FPSIMD/SVE/SME state, and the code to do this is never used. Protected KVM still needs to save/restore the host FPSIMD/SVE state to avoid leaking guest state to the host (and to avoid revealing to the host whether the guest used FPSIMD/SVE/SME), and that code needs to be retained. Remove the unused code and data structures. To avoid the need for a stub copy of kvm_hyp_save_fpsimd_host() in the VHE hyp code, the nVHE/hVHE version is moved into the shared switch header, where it is only invoked when KVM is in protected mode. Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> Reviewed-by: Mark Brown <broonie@xxxxxxxxxx> Tested-by: Mark Brown <broonie@xxxxxxxxxx> Acked-by: Will Deacon <will@xxxxxxxxxx> Cc: Catalin Marinas <catalin.marinas@xxxxxxx> Cc: Fuad Tabba <tabba@xxxxxxxxxx> Cc: Marc Zyngier <maz@xxxxxxxxxx> Cc: Oliver Upton <oliver.upton@xxxxxxxxx> Reviewed-by: Oliver Upton <oliver.upton@xxxxxxxxx> Link: https://lore.kernel.org/r/20250210195226.1215254-3-mark.rutland@xxxxxxx Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/include/asm/kvm_host.h | 18 ++++-------------- arch/arm64/kvm/arm.c | 8 -------- arch/arm64/kvm/fpsimd.c | 2 -- arch/arm64/kvm/hyp/include/hyp/switch.h | 25 +++++++++++++++++++++++-- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 2 +- arch/arm64/kvm/hyp/nvhe/switch.c | 28 ---------------------------- arch/arm64/kvm/hyp/vhe/switch.c | 8 -------- 7 files changed, 28 insertions(+), 63 deletions(-) --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -602,23 +602,13 @@ struct kvm_host_data { struct kvm_cpu_context host_ctxt; /* - * All pointers in this union are hyp VA. + * Hyp VA. * sve_state is only used in pKVM and if system_supports_sve(). */ - union { - struct user_fpsimd_state *fpsimd_state; - struct cpu_sve_state *sve_state; - }; + struct cpu_sve_state *sve_state; - union { - /* HYP VA pointer to the host storage for FPMR */ - u64 *fpmr_ptr; - /* - * Used by pKVM only, as it needs to provide storage - * for the host - */ - u64 fpmr; - }; + /* Used by pKVM only. */ + u64 fpmr; /* Ownership of the FP regs */ enum { --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -2476,14 +2476,6 @@ static void finalize_init_hyp_mode(void) per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->sve_state = kern_hyp_va(sve_state); } - } else { - for_each_possible_cpu(cpu) { - struct user_fpsimd_state *fpsimd_state; - - fpsimd_state = &per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->host_ctxt.fp_regs; - per_cpu_ptr_nvhe_sym(kvm_host_data, cpu)->fpsimd_state = - kern_hyp_va(fpsimd_state); - } } } --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -64,8 +64,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vc */ fpsimd_save_and_flush_cpu_state(); *host_data_ptr(fp_owner) = FP_STATE_FREE; - *host_data_ptr(fpsimd_state) = NULL; - *host_data_ptr(fpmr_ptr) = NULL; vcpu_clear_flag(vcpu, HOST_SVE_ENABLED); if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) --- a/arch/arm64/kvm/hyp/include/hyp/switch.h +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h @@ -344,7 +344,28 @@ static inline void __hyp_sve_save_host(v true); } -static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu); +static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu) +{ + /* + * Non-protected kvm relies on the host restoring its sve state. + * Protected kvm restores the host's sve state as not to reveal that + * fpsimd was used by a guest nor leak upper sve bits. + */ + if (system_supports_sve()) { + __hyp_sve_save_host(); + + /* Re-enable SVE traps if not supported for the guest vcpu. */ + if (!vcpu_has_sve(vcpu)) + cpacr_clear_set(CPACR_ELx_ZEN, 0); + + } else { + __fpsimd_save_state(host_data_ptr(host_ctxt.fp_regs)); + } + + if (kvm_has_fpmr(kern_hyp_va(vcpu->kvm))) + *host_data_ptr(fpmr) = read_sysreg_s(SYS_FPMR); +} + /* * We trap the first access to the FP/SIMD to save the host context and @@ -394,7 +415,7 @@ static bool kvm_hyp_handle_fpsimd(struct isb(); /* Write out the host state if it's in the registers */ - if (host_owns_fp_regs()) + if (is_protected_kvm_enabled() && host_owns_fp_regs()) kvm_hyp_save_fpsimd_host(vcpu); /* Restore the guest state */ --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -83,7 +83,7 @@ static void fpsimd_sve_sync(struct kvm_v if (system_supports_sve()) __hyp_sve_restore_host(); else - __fpsimd_restore_state(*host_data_ptr(fpsimd_state)); + __fpsimd_restore_state(host_data_ptr(host_ctxt.fp_regs)); if (has_fpmr) write_sysreg_s(*host_data_ptr(fpmr), SYS_FPMR); --- a/arch/arm64/kvm/hyp/nvhe/switch.c +++ b/arch/arm64/kvm/hyp/nvhe/switch.c @@ -193,34 +193,6 @@ static bool kvm_handle_pvm_sys64(struct kvm_handle_pvm_sysreg(vcpu, exit_code)); } -static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu) -{ - /* - * Non-protected kvm relies on the host restoring its sve state. - * Protected kvm restores the host's sve state as not to reveal that - * fpsimd was used by a guest nor leak upper sve bits. - */ - if (unlikely(is_protected_kvm_enabled() && system_supports_sve())) { - __hyp_sve_save_host(); - - /* Re-enable SVE traps if not supported for the guest vcpu. */ - if (!vcpu_has_sve(vcpu)) - cpacr_clear_set(CPACR_ELx_ZEN, 0); - - } else { - __fpsimd_save_state(*host_data_ptr(fpsimd_state)); - } - - if (kvm_has_fpmr(kern_hyp_va(vcpu->kvm))) { - u64 val = read_sysreg_s(SYS_FPMR); - - if (unlikely(is_protected_kvm_enabled())) - *host_data_ptr(fpmr) = val; - else - **host_data_ptr(fpmr_ptr) = val; - } -} - static const exit_handler_fn hyp_exit_handlers[] = { [0 ... ESR_ELx_EC_MAX] = NULL, [ESR_ELx_EC_CP15_32] = kvm_hyp_handle_cp15_32, --- a/arch/arm64/kvm/hyp/vhe/switch.c +++ b/arch/arm64/kvm/hyp/vhe/switch.c @@ -309,14 +309,6 @@ static bool kvm_hyp_handle_eret(struct k return true; } -static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu) -{ - __fpsimd_save_state(*host_data_ptr(fpsimd_state)); - - if (kvm_has_fpmr(vcpu->kvm)) - **host_data_ptr(fpmr_ptr) = read_sysreg_s(SYS_FPMR); -} - static bool kvm_hyp_handle_tlbi_el2(struct kvm_vcpu *vcpu, u64 *exit_code) { int ret = -EINVAL; Patches currently in stable-queue which might be from mark.rutland@xxxxxxx are queue-6.12/kvm-arm64-remove-host-fpsimd-saving-for-non-protected-kvm.patch queue-6.12/kvm-arm64-mark-some-header-functions-as-inline.patch queue-6.12/kvm-arm64-eagerly-switch-zcr_el-1-2.patch queue-6.12/kvm-arm64-unconditionally-save-flush-host-fpsimd-sve-sme-state.patch queue-6.12/kvm-arm64-refactor-exit-handlers.patch queue-6.12/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.zen.patch queue-6.12/kvm-arm64-remove-vhe-host-restore-of-cpacr_el1.smen.patch
