From: Mark Rutland <mark.rutland@xxxxxxx> commit 459f059be702056d91537b99a129994aa6ccdd35 upstream. When KVM is in VHE mode, the host kernel tries to save and restore the configuration of CPACR_EL1.ZEN (i.e. CPTR_EL2.ZEN when HCR_EL2.E2H=1) across kvm_arch_vcpu_load_fp() and kvm_arch_vcpu_put_fp(), since the configuration may be clobbered by hyp when running a vCPU. This logic is currently redundant. The VHE hyp code unconditionally configures CPTR_EL2.ZEN to 0b01 when returning to the host, permitting host kernel usage of SVE. Now that the host eagerly saves and unbinds its own FPSIMD/SVE/SME state, there's no need to save/restore the state of the EL0 SVE trap. The kernel can safely save/restore state without trapping, as described above, and will restore userspace state (including trap controls) before returning to userspace. Remove the redundant logic. 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/20250210195226.1215254-4-mark.rutland@xxxxxxx Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx> [Rework for refactoring of where the flags are stored -- broonie] Signed-off-by: Mark Brown <broonie@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/arm64/include/asm/kvm_host.h | 2 -- arch/arm64/kvm/fpsimd.c | 16 ---------------- 2 files changed, 18 deletions(-) --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -891,8 +891,6 @@ struct kvm_vcpu_arch { /* Save TRBE context if active */ #define DEBUG_STATE_SAVE_TRBE __vcpu_single_flag(iflags, BIT(6)) -/* SVE enabled for host EL0 */ -#define HOST_SVE_ENABLED __vcpu_single_flag(sflags, BIT(0)) /* SME enabled for EL0 */ #define HOST_SME_ENABLED __vcpu_single_flag(sflags, BIT(1)) /* Physical CPU not in supported_cpus */ --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -65,10 +65,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vc fpsimd_save_and_flush_cpu_state(); *host_data_ptr(fp_owner) = FP_STATE_FREE; - vcpu_clear_flag(vcpu, HOST_SVE_ENABLED); - if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN) - vcpu_set_flag(vcpu, HOST_SVE_ENABLED); - if (system_supports_sme()) { vcpu_clear_flag(vcpu, HOST_SME_ENABLED); if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN) @@ -202,18 +198,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcp * when needed. */ fpsimd_save_and_flush_cpu_state(); - } else if (has_vhe() && system_supports_sve()) { - /* - * The FPSIMD/SVE state in the CPU has not been touched, and we - * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been - * reset by kvm_reset_cptr_el2() in the Hyp code, disabling SVE - * for EL0. To avoid spurious traps, restore the trap state - * seen by kvm_arch_vcpu_load_fp(): - */ - if (vcpu_get_flag(vcpu, HOST_SVE_ENABLED)) - sysreg_clear_set(CPACR_EL1, 0, CPACR_EL1_ZEN_EL0EN); - else - sysreg_clear_set(CPACR_EL1, CPACR_EL1_ZEN_EL0EN, 0); } local_irq_restore(flags); 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
