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>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Fuad Tabba <tabba@xxxxxxxxxx>
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Oliver Upton <oliver.upton@xxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 1 -
arch/arm64/kvm/fpsimd.c | 16 ----------------
2 files changed, 17 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index f56c07568591f..ed6841bf21b22 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -615,7 +615,6 @@ struct cpu_sve_state {
struct kvm_host_data {
#define KVM_HOST_DATA_FLAG_HAS_SPE 0
#define KVM_HOST_DATA_FLAG_HAS_TRBE 1
-#define KVM_HOST_DATA_FLAG_HOST_SVE_ENABLED 2
#define KVM_HOST_DATA_FLAG_HOST_SME_ENABLED 3
#define KVM_HOST_DATA_FLAG_TRBE_ENABLED 4
#define KVM_HOST_DATA_FLAG_EL1_TRACING_CONFIGURED 5
diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c
index 332cb3904e68b..4ff0dee1a403f 100644
--- a/arch/arm64/kvm/fpsimd.c
+++ b/arch/arm64/kvm/fpsimd.c
@@ -65,10 +65,6 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu)
fpsimd_save_and_flush_cpu_state();
*host_data_ptr(fp_owner) = FP_STATE_FREE;
- host_data_clear_flag(HOST_SVE_ENABLED);
- if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)
- host_data_set_flag(HOST_SVE_ENABLED);
-
if (system_supports_sme()) {
host_data_clear_flag(HOST_SME_ENABLED);
if (read_sysreg(cpacr_el1) & CPACR_EL1_SMEN_EL0EN)
@@ -202,18 +198,6 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu)
* 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 (host_data_test_flag(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);
--
2.30.2
