KVM: arm64: Rework SVE host-save/guest-restore

mainline inclusion
from mainline-v5.13-rc1~76^2
commit 52029198
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=52029198c1cec1e21513d74f87363a0408f28650

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

In order to keep the code readable, move the host-save/guest-restore
sequences in their own functions, with the following changes:
- the hypervisor ZCR is now set from C code
- ZCR_EL2 is always used as the EL2 accessor

This results in some minor assembler macro rework.
No functional change intended.
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/include/asm/fpsimdmacros.h

@@ -234,8 +234,7 @@
 		str		w\nxtmp, [\xpfpsr, #4]
 .endm
 
-.macro sve_load nxbase, xpfpsr, xvqminus1, nxtmp, xtmp2
-		sve_load_vq	\xvqminus1, x\nxtmp, \xtmp2
+.macro __sve_load nxbase, xpfpsr, nxtmp
  _for n, 0, 31,	_sve_ldr_v	\n, \nxbase, \n - 34
 		_sve_ldr_p	0, \nxbase
 		_sve_wrffr	0
@@ -246,3 +245,8 @@
 		ldr		w\nxtmp, [\xpfpsr, #4]
 		msr		fpcr, x\nxtmp
 .endm
+
+.macro sve_load nxbase, xpfpsr, xvqminus1, nxtmp, xtmp2
+		sve_load_vq	\xvqminus1, x\nxtmp, \xtmp2
+		__sve_load	\nxbase, \xpfpsr, \nxtmp
+.endm

arch/arm64/include/asm/kvm_hyp.h

@@ -90,7 +90,7 @@ void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu);
 void __fpsimd_save_state(struct user_fpsimd_state *fp_regs);
 void __fpsimd_restore_state(struct user_fpsimd_state *fp_regs);
 void __sve_save_state(void *sve_pffr, u32 *fpsr);
-void __sve_restore_state(void *sve_pffr, u32 *fpsr, unsigned int vqminus1);
+void __sve_restore_state(void *sve_pffr, u32 *fpsr);
 
 #ifndef __KVM_NVHE_HYPERVISOR__
 void activate_traps_vhe_load(struct kvm_vcpu *vcpu);

arch/arm64/kvm/hyp/fpsimd.S

@@ -21,7 +21,7 @@ SYM_FUNC_START(__fpsimd_restore_state)
 SYM_FUNC_END(__fpsimd_restore_state)
 
 SYM_FUNC_START(__sve_restore_state)
-	sve_load 0, x1, x2, 3, x4
+	__sve_load 0, x1, 2
 	ret
 SYM_FUNC_END(__sve_restore_state)
 

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

@@ -194,6 +194,24 @@ static inline bool __populate_fault_info(struct kvm_vcpu *vcpu)
 	return true;
 }
 
+static inline void __hyp_sve_save_host(struct kvm_vcpu *vcpu)
+{
+	struct thread_struct *thread;
+
+	thread = container_of(vcpu->arch.host_fpsimd_state, struct thread_struct,
+			      uw.fpsimd_state);
+
+	__sve_save_state(sve_pffr(thread), &vcpu->arch.host_fpsimd_state->fpsr);
+}
+
+static inline void __hyp_sve_restore_guest(struct kvm_vcpu *vcpu)
+{
+	sve_cond_update_zcr_vq(vcpu_sve_max_vq(vcpu) - 1, SYS_ZCR_EL2);
+	__sve_restore_state(vcpu_sve_pffr(vcpu),
+			    &vcpu->arch.ctxt.fp_regs.fpsr);
+	write_sysreg_el1(__vcpu_sys_reg(vcpu, ZCR_EL1), SYS_ZCR);
+}
+
 /* Check for an FPSIMD/SVE trap and handle as appropriate */
 static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
 {
@@ -250,28 +268,18 @@ static inline bool __hyp_handle_fpsimd(struct kvm_vcpu *vcpu)
 		 * In the SVE case, VHE is assumed: it is enforced by
 		 * Kconfig and kvm_arch_init().
 		 */
-		if (sve_host) {
-			struct thread_struct *thread = container_of(
-				vcpu->arch.host_fpsimd_state,
-				struct thread_struct, uw.fpsimd_state);
-
-			__sve_save_state(sve_pffr(thread),
-					 &vcpu->arch.host_fpsimd_state->fpsr);
-		} else {
+		if (sve_host)
+			__hyp_sve_save_host(vcpu);
+		else
 			__fpsimd_save_state(vcpu->arch.host_fpsimd_state);
-		}
 
 		vcpu->arch.flags &= ~KVM_ARM64_FP_HOST;
 	}
 
-	if (sve_guest) {
-		__sve_restore_state(vcpu_sve_pffr(vcpu),
-				    &vcpu->arch.ctxt.fp_regs.fpsr,
-				    vcpu_sve_max_vq(vcpu) - 1);
-		write_sysreg_el1(__vcpu_sys_reg(vcpu, ZCR_EL1), SYS_ZCR);
-	} else {
+	if (sve_guest)
+		__hyp_sve_restore_guest(vcpu);
+	else
 		__fpsimd_restore_state(&vcpu->arch.ctxt.fp_regs);
-	}
 
 	/* Skip restoring fpexc32 for AArch64 guests */
 	if (!(read_sysreg(hcr_el2) & HCR_RW))