KVM: arm64: Save/restore SVE state for nVHE

mainline inclusion
from mainline-v5.13-rc1~76^2
commit 8c8010d6
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I5ITJT
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=8c8010d69c1322734a272eb95dbbf42b5190e565

-------------------------------------------------

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: NWill Deacon <will@kernel.org>
Signed-off-by: NMarc Zyngier <maz@kernel.org>
Signed-off-by: NWang ShaoBo <bobo.shaobowang@huawei.com>

arch/arm64/kvm/fpsimd.c

@@ -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

@@ -215,25 +215,19 @@ 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);
@@ -243,31 +237,28 @@ static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
 
 	vcpu->stat.fp_asimd_exit_stat++;
 	/* Don't handle SVE traps for non-SVE vcpus here: */
-	if (!sve_guest)
-		if (esr_ec != ESR_ELx_EC_FP_ASIMD)
-			return false;
+	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

@@ -40,9 +40,9 @@ 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);
 	}