Commit ef3be860 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: Add save/restore support for FPMR 



Just like the rest of the FP/SIMD state, FPMR needs to be context
switched.

The only interesting thing here is that we need to treat the pKVM
part a bit differently, as the host FP state is never written back
to the vcpu thread, but instead stored locally and eagerly restored.

Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Tested-by: default avatarMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240820131802.3547589-5-maz@kernel.org


Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 7d9c1ed6

arch/arm64/include/asm/kvm_host.h

+10 −0
Original line number Diff line number Diff line
@@ -599,6 +599,16 @@ struct kvm_host_data { 
		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;

	};



	/* Ownership of the FP regs */

	enum {

		FP_STATE_FREE,

arch/arm64/kvm/fpsimd.c

+1 −0
Original line number Diff line number Diff line
@@ -63,6 +63,7 @@ void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu) 
	 */

	*host_data_ptr(fp_owner) = FP_STATE_HOST_OWNED;

	*host_data_ptr(fpsimd_state) = kern_hyp_va(&current->thread.uw.fpsimd_state);

	*host_data_ptr(fpmr_ptr) = kern_hyp_va(&current->thread.uw.fpmr);



	vcpu_clear_flag(vcpu, HOST_SVE_ENABLED);

	if (read_sysreg(cpacr_el1) & CPACR_EL1_ZEN_EL0EN)

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

+3 −0
Original line number Diff line number Diff line
@@ -404,6 +404,9 @@ static bool kvm_hyp_handle_fpsimd(struct kvm_vcpu *vcpu, u64 *exit_code) 
	else

		__fpsimd_restore_state(&vcpu->arch.ctxt.fp_regs);



	if (kvm_has_fpmr(kern_hyp_va(vcpu->kvm)))

		write_sysreg_s(__vcpu_sys_reg(vcpu, FPMR), SYS_FPMR);



	/* Skip restoring fpexc32 for AArch64 guests */

	if (!(read_sysreg(hcr_el2) & HCR_RW))

		write_sysreg(__vcpu_sys_reg(vcpu, FPEXC32_EL2), fpexc32_el2);

arch/arm64/kvm/hyp/nvhe/hyp-main.c

+9 −0
Original line number Diff line number Diff line
@@ -62,6 +62,8 @@ static void fpsimd_sve_flush(void) 


static void fpsimd_sve_sync(struct kvm_vcpu *vcpu)

{

	bool has_fpmr;



	if (!guest_owns_fp_regs())

		return;
@@ -73,11 +75,18 @@ static void fpsimd_sve_sync(struct kvm_vcpu *vcpu) 
	else

		__fpsimd_save_state(&vcpu->arch.ctxt.fp_regs);



	has_fpmr = kvm_has_fpmr(kern_hyp_va(vcpu->kvm));

	if (has_fpmr)

		__vcpu_sys_reg(vcpu, FPMR) = read_sysreg_s(SYS_FPMR);



	if (system_supports_sve())

		__hyp_sve_restore_host();

	else

		__fpsimd_restore_state(*host_data_ptr(fpsimd_state));



	if (has_fpmr)

		write_sysreg_s(*host_data_ptr(fpmr), SYS_FPMR);



	*host_data_ptr(fp_owner) = FP_STATE_HOST_OWNED;

}

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

+9 −0
Original line number Diff line number Diff line
@@ -198,6 +198,15 @@ static void kvm_hyp_save_fpsimd_host(struct kvm_vcpu *vcpu) 
	} 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[] = {