Commit 8c8010d6 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: Save/restore SVE state for nVHE 



Implement the SVE save/restore for nVHE, following a similar
logic to that of the VHE implementation:

- the SVE state is switched on trap from EL1 to EL2

- no further changes to ZCR_EL2 occur as long as the guest isn't
  preempted or exit to userspace

- ZCR_EL2 is reset to its default value on the first SVE access from
  the host EL1, and ZCR_EL1 restored to the default guest value in
  vcpu_put()

Acked-by: default avatarWill Deacon <will@kernel.org>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent beed0906

arch/arm64/kvm/fpsimd.c

+8 −2
Original line number Diff line number Diff line
@@ -121,11 +121,17 @@ void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) 
	local_irq_save(flags);



	if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) {

		if (guest_has_sve)

		if (guest_has_sve) {

			__vcpu_sys_reg(vcpu, ZCR_EL1) = read_sysreg_el1(SYS_ZCR);



			/* Restore the VL that was saved when bound to the CPU */

			if (!has_vhe())

				sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1,

						       SYS_ZCR_EL1);

		}



		fpsimd_save_and_flush_cpu_state();

	} else if (host_has_sve) {

	} else if (has_vhe() && host_has_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

arch/arm64/kvm/hyp/include/hyp/switch.h

+13 −24
Original line number Diff line number Diff line
@@ -217,25 +217,19 @@ static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu) 
/* Check for an FPSIMD/SVE trap and handle as appropriate */

static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)

{

	bool vhe, sve_guest, sve_host;

	bool sve_guest, sve_host;

	u8 esr_ec;

	u64 reg;



	if (!system_supports_fpsimd())

		return false;



	/*

	 * Currently system_supports_sve() currently implies has_vhe(),

	 * so the check is redundant. However, has_vhe() can be determined

	 * statically and helps the compiler remove dead code.

	 */

	if (has_vhe() && system_supports_sve()) {

	if (system_supports_sve()) {

		sve_guest = vcpu_has_sve(vcpu);

		sve_host = vcpu->arch.flags & KVM_ARM64_HOST_SVE_IN_USE;

		vhe = true;

	} else {

		sve_guest = false;

		sve_host = false;

		vhe = has_vhe();

	}



	esr_ec = kvm_vcpu_trap_get_class(vcpu);
@@ -244,31 +238,26 @@ static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu) 
		return false;



	/* Don't handle SVE traps for non-SVE vcpus here: */

	if (!sve_guest)

		if (esr_ec != ESR_ELx_EC_FP_ASIMD)

	if (!sve_guest && esr_ec != ESR_ELx_EC_FP_ASIMD)

		return false;



	/* Valid trap.  Switch the context: */



	if (vhe) {

		u64 reg = read_sysreg(cpacr_el1) | CPACR_EL1_FPEN;



	if (has_vhe()) {

		reg = CPACR_EL1_FPEN;

		if (sve_guest)

			reg |= CPACR_EL1_ZEN;



		write_sysreg(reg, cpacr_el1);

		sysreg_clear_set(cpacr_el1, 0, reg);

	} else {

		write_sysreg(read_sysreg(cptr_el2) & ~(u64)CPTR_EL2_TFP,

			     cptr_el2);

	}

		reg = CPTR_EL2_TFP;

		if (sve_guest)

			reg |= CPTR_EL2_TZ;



		sysreg_clear_set(cptr_el2, reg, 0);

	}

	isb();



	if (vcpu->arch.flags & KVM_ARM64_FP_HOST) {

		/*

		 * In the SVE case, VHE is assumed: it is enforced by

		 * Kconfig and kvm_arch_init().

		 */

		if (sve_host)

			__hyp_sve_save_host(vcpu);

		else

arch/arm64/kvm/hyp/nvhe/switch.c

+2 −2
Original line number Diff line number Diff line
@@ -41,9 +41,9 @@ static void __activate_traps(struct kvm_vcpu *vcpu) 
	__activate_traps_common(vcpu);



	val = CPTR_EL2_DEFAULT;

	val |= CPTR_EL2_TTA | CPTR_EL2_TZ | CPTR_EL2_TAM;

	val |= CPTR_EL2_TTA | CPTR_EL2_TAM;

	if (!update_fp_enabled(vcpu)) {

		val |= CPTR_EL2_TFP;

		val |= CPTR_EL2_TFP | CPTR_EL2_TZ;

		__activate_traps_fpsimd32(vcpu);

	}