[PATCH v14 06/17] RISC-V: KVM: Implement VCPU world-switch

From: Anup Patel
Date: Mon Aug 31 2020 - 08:31:51 EST

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This patch implements the VCPU world-switch for KVM RISC-V.

The KVM RISC-V world-switch (i.e. __kvm_riscv_switch_to()) mostly
switches general purpose registers, SSTATUS, STVEC, SSCRATCH and
HSTATUS CSRs. Other CSRs are switched via vcpu_load() and vcpu_put()
interface in kvm_arch_vcpu_load() and kvm_arch_vcpu_put() functions
respectively.

Signed-off-by: Anup Patel <anup.patel@xxxxxxx>
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Reviewed-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Reviewed-by: Alexander Graf <graf@xxxxxxxxxx>
---
arch/riscv/include/asm/kvm_host.h | 10 +-
arch/riscv/kernel/asm-offsets.c | 78 ++++++++++++
arch/riscv/kvm/Makefile | 2 +-
arch/riscv/kvm/vcpu.c | 30 ++++-
arch/riscv/kvm/vcpu_switch.S | 203 ++++++++++++++++++++++++++++++
5 files changed, 319 insertions(+), 4 deletions(-)
create mode 100644 arch/riscv/kvm/vcpu_switch.S

diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
index 8829bed4517f..e2f5523e26de 100644
--- a/arch/riscv/include/asm/kvm_host.h
+++ b/arch/riscv/include/asm/kvm_host.h
@@ -121,6 +121,14 @@ struct kvm_vcpu_arch {
/* ISA feature bits (similar to MISA) */
unsigned long isa;

+ /* SSCRATCH, STVEC, and SCOUNTEREN of Host */
+ unsigned long host_sscratch;
+ unsigned long host_stvec;
+ unsigned long host_scounteren;
+
+ /* CPU context of Host */
+ struct kvm_cpu_context host_context;
+
/* CPU context of Guest VCPU */
struct kvm_cpu_context guest_context;

@@ -170,7 +178,7 @@ int kvm_riscv_vcpu_mmio_return(struct kvm_vcpu *vcpu, struct kvm_run *run);
int kvm_riscv_vcpu_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
struct kvm_cpu_trap *trap);

-static inline void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch) {}
+void __kvm_riscv_switch_to(struct kvm_vcpu_arch *vcpu_arch);

int kvm_riscv_vcpu_set_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
int kvm_riscv_vcpu_unset_interrupt(struct kvm_vcpu *vcpu, unsigned int irq);
diff --git a/arch/riscv/kernel/asm-offsets.c b/arch/riscv/kernel/asm-offsets.c
index db203442c08f..83425ce20804 100644
--- a/arch/riscv/kernel/asm-offsets.c
+++ b/arch/riscv/kernel/asm-offsets.c
@@ -7,7 +7,9 @@
#define GENERATING_ASM_OFFSETS

#include <linux/kbuild.h>
+#include <linux/mm.h>
#include <linux/sched.h>
+#include <asm/kvm_host.h>
#include <asm/thread_info.h>
#include <asm/ptrace.h>

@@ -106,6 +108,82 @@ void asm_offsets(void)
OFFSET(PT_BADADDR, pt_regs, badaddr);
OFFSET(PT_CAUSE, pt_regs, cause);

+ OFFSET(KVM_ARCH_GUEST_ZERO, kvm_vcpu_arch, guest_context.zero);
+ OFFSET(KVM_ARCH_GUEST_RA, kvm_vcpu_arch, guest_context.ra);
+ OFFSET(KVM_ARCH_GUEST_SP, kvm_vcpu_arch, guest_context.sp);
+ OFFSET(KVM_ARCH_GUEST_GP, kvm_vcpu_arch, guest_context.gp);
+ OFFSET(KVM_ARCH_GUEST_TP, kvm_vcpu_arch, guest_context.tp);
+ OFFSET(KVM_ARCH_GUEST_T0, kvm_vcpu_arch, guest_context.t0);
+ OFFSET(KVM_ARCH_GUEST_T1, kvm_vcpu_arch, guest_context.t1);
+ OFFSET(KVM_ARCH_GUEST_T2, kvm_vcpu_arch, guest_context.t2);
+ OFFSET(KVM_ARCH_GUEST_S0, kvm_vcpu_arch, guest_context.s0);
+ OFFSET(KVM_ARCH_GUEST_S1, kvm_vcpu_arch, guest_context.s1);
+ OFFSET(KVM_ARCH_GUEST_A0, kvm_vcpu_arch, guest_context.a0);
+ OFFSET(KVM_ARCH_GUEST_A1, kvm_vcpu_arch, guest_context.a1);
+ OFFSET(KVM_ARCH_GUEST_A2, kvm_vcpu_arch, guest_context.a2);
+ OFFSET(KVM_ARCH_GUEST_A3, kvm_vcpu_arch, guest_context.a3);
+ OFFSET(KVM_ARCH_GUEST_A4, kvm_vcpu_arch, guest_context.a4);
+ OFFSET(KVM_ARCH_GUEST_A5, kvm_vcpu_arch, guest_context.a5);
+ OFFSET(KVM_ARCH_GUEST_A6, kvm_vcpu_arch, guest_context.a6);
+ OFFSET(KVM_ARCH_GUEST_A7, kvm_vcpu_arch, guest_context.a7);
+ OFFSET(KVM_ARCH_GUEST_S2, kvm_vcpu_arch, guest_context.s2);
+ OFFSET(KVM_ARCH_GUEST_S3, kvm_vcpu_arch, guest_context.s3);
+ OFFSET(KVM_ARCH_GUEST_S4, kvm_vcpu_arch, guest_context.s4);
+ OFFSET(KVM_ARCH_GUEST_S5, kvm_vcpu_arch, guest_context.s5);
+ OFFSET(KVM_ARCH_GUEST_S6, kvm_vcpu_arch, guest_context.s6);
+ OFFSET(KVM_ARCH_GUEST_S7, kvm_vcpu_arch, guest_context.s7);
+ OFFSET(KVM_ARCH_GUEST_S8, kvm_vcpu_arch, guest_context.s8);
+ OFFSET(KVM_ARCH_GUEST_S9, kvm_vcpu_arch, guest_context.s9);
+ OFFSET(KVM_ARCH_GUEST_S10, kvm_vcpu_arch, guest_context.s10);
+ OFFSET(KVM_ARCH_GUEST_S11, kvm_vcpu_arch, guest_context.s11);
+ OFFSET(KVM_ARCH_GUEST_T3, kvm_vcpu_arch, guest_context.t3);
+ OFFSET(KVM_ARCH_GUEST_T4, kvm_vcpu_arch, guest_context.t4);
+ OFFSET(KVM_ARCH_GUEST_T5, kvm_vcpu_arch, guest_context.t5);
+ OFFSET(KVM_ARCH_GUEST_T6, kvm_vcpu_arch, guest_context.t6);
+ OFFSET(KVM_ARCH_GUEST_SEPC, kvm_vcpu_arch, guest_context.sepc);
+ OFFSET(KVM_ARCH_GUEST_SSTATUS, kvm_vcpu_arch, guest_context.sstatus);
+ OFFSET(KVM_ARCH_GUEST_HSTATUS, kvm_vcpu_arch, guest_context.hstatus);
+ OFFSET(KVM_ARCH_GUEST_SCOUNTEREN, kvm_vcpu_arch, guest_csr.scounteren);
+
+ OFFSET(KVM_ARCH_HOST_ZERO, kvm_vcpu_arch, host_context.zero);
+ OFFSET(KVM_ARCH_HOST_RA, kvm_vcpu_arch, host_context.ra);
+ OFFSET(KVM_ARCH_HOST_SP, kvm_vcpu_arch, host_context.sp);
+ OFFSET(KVM_ARCH_HOST_GP, kvm_vcpu_arch, host_context.gp);
+ OFFSET(KVM_ARCH_HOST_TP, kvm_vcpu_arch, host_context.tp);
+ OFFSET(KVM_ARCH_HOST_T0, kvm_vcpu_arch, host_context.t0);
+ OFFSET(KVM_ARCH_HOST_T1, kvm_vcpu_arch, host_context.t1);
+ OFFSET(KVM_ARCH_HOST_T2, kvm_vcpu_arch, host_context.t2);
+ OFFSET(KVM_ARCH_HOST_S0, kvm_vcpu_arch, host_context.s0);
+ OFFSET(KVM_ARCH_HOST_S1, kvm_vcpu_arch, host_context.s1);
+ OFFSET(KVM_ARCH_HOST_A0, kvm_vcpu_arch, host_context.a0);
+ OFFSET(KVM_ARCH_HOST_A1, kvm_vcpu_arch, host_context.a1);
+ OFFSET(KVM_ARCH_HOST_A2, kvm_vcpu_arch, host_context.a2);
+ OFFSET(KVM_ARCH_HOST_A3, kvm_vcpu_arch, host_context.a3);
+ OFFSET(KVM_ARCH_HOST_A4, kvm_vcpu_arch, host_context.a4);
+ OFFSET(KVM_ARCH_HOST_A5, kvm_vcpu_arch, host_context.a5);
+ OFFSET(KVM_ARCH_HOST_A6, kvm_vcpu_arch, host_context.a6);
+ OFFSET(KVM_ARCH_HOST_A7, kvm_vcpu_arch, host_context.a7);
+ OFFSET(KVM_ARCH_HOST_S2, kvm_vcpu_arch, host_context.s2);
+ OFFSET(KVM_ARCH_HOST_S3, kvm_vcpu_arch, host_context.s3);
+ OFFSET(KVM_ARCH_HOST_S4, kvm_vcpu_arch, host_context.s4);
+ OFFSET(KVM_ARCH_HOST_S5, kvm_vcpu_arch, host_context.s5);
+ OFFSET(KVM_ARCH_HOST_S6, kvm_vcpu_arch, host_context.s6);
+ OFFSET(KVM_ARCH_HOST_S7, kvm_vcpu_arch, host_context.s7);
+ OFFSET(KVM_ARCH_HOST_S8, kvm_vcpu_arch, host_context.s8);
+ OFFSET(KVM_ARCH_HOST_S9, kvm_vcpu_arch, host_context.s9);
+ OFFSET(KVM_ARCH_HOST_S10, kvm_vcpu_arch, host_context.s10);
+ OFFSET(KVM_ARCH_HOST_S11, kvm_vcpu_arch, host_context.s11);
+ OFFSET(KVM_ARCH_HOST_T3, kvm_vcpu_arch, host_context.t3);
+ OFFSET(KVM_ARCH_HOST_T4, kvm_vcpu_arch, host_context.t4);
+ OFFSET(KVM_ARCH_HOST_T5, kvm_vcpu_arch, host_context.t5);
+ OFFSET(KVM_ARCH_HOST_T6, kvm_vcpu_arch, host_context.t6);
+ OFFSET(KVM_ARCH_HOST_SEPC, kvm_vcpu_arch, host_context.sepc);
+ OFFSET(KVM_ARCH_HOST_SSTATUS, kvm_vcpu_arch, host_context.sstatus);
+ OFFSET(KVM_ARCH_HOST_HSTATUS, kvm_vcpu_arch, host_context.hstatus);
+ OFFSET(KVM_ARCH_HOST_SSCRATCH, kvm_vcpu_arch, host_sscratch);
+ OFFSET(KVM_ARCH_HOST_STVEC, kvm_vcpu_arch, host_stvec);
+ OFFSET(KVM_ARCH_HOST_SCOUNTEREN, kvm_vcpu_arch, host_scounteren);
+
/*
* THREAD_{F,X}* might be larger than a S-type offset can handle, but
* these are used in performance-sensitive assembly so we can't resort
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index 37b5a59d4f4f..845579273727 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -8,6 +8,6 @@ ccflags-y := -Ivirt/kvm -Iarch/riscv/kvm

kvm-objs := $(common-objs-y)

-kvm-objs += main.o vm.o mmu.o vcpu.o vcpu_exit.o
+kvm-objs += main.o vm.o mmu.o vcpu.o vcpu_exit.o vcpu_switch.o

obj-$(CONFIG_KVM) += kvm.o
diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
index e38eedc784a7..43962a25fa55 100644
--- a/arch/riscv/kvm/vcpu.c
+++ b/arch/riscv/kvm/vcpu.c
@@ -580,14 +580,40 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,

void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
{
- /* TODO: */
+ struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+ csr_write(CSR_VSSTATUS, csr->vsstatus);
+ csr_write(CSR_HIE, csr->hie);
+ csr_write(CSR_VSTVEC, csr->vstvec);
+ csr_write(CSR_VSSCRATCH, csr->vsscratch);
+ csr_write(CSR_VSEPC, csr->vsepc);
+ csr_write(CSR_VSCAUSE, csr->vscause);
+ csr_write(CSR_VSTVAL, csr->vstval);
+ csr_write(CSR_HVIP, csr->hvip);
+ csr_write(CSR_VSATP, csr->vsatp);

kvm_riscv_stage2_update_hgatp(vcpu);
+
+ vcpu->cpu = cpu;
}

void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
- /* TODO: */
+ struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;
+
+ vcpu->cpu = -1;
+
+ csr_write(CSR_HGATP, 0);
+
+ csr->vsstatus = csr_read(CSR_VSSTATUS);
+ csr->hie = csr_read(CSR_HIE);
+ csr->vstvec = csr_read(CSR_VSTVEC);
+ csr->vsscratch = csr_read(CSR_VSSCRATCH);
+ csr->vsepc = csr_read(CSR_VSEPC);
+ csr->vscause = csr_read(CSR_VSCAUSE);
+ csr->vstval = csr_read(CSR_VSTVAL);
+ csr->hvip = csr_read(CSR_HVIP);
+ csr->vsatp = csr_read(CSR_VSATP);
}

static void kvm_riscv_check_vcpu_requests(struct kvm_vcpu *vcpu)
diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S
new file mode 100644
index 000000000000..5174b025ff4e
--- /dev/null
+++ b/arch/riscv/kvm/vcpu_switch.S
@@ -0,0 +1,203 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 Western Digital Corporation or its affiliates.
+ *
+ * Authors:
+ * Anup Patel <anup.patel@xxxxxxx>
+ */
+
+#include <linux/linkage.h>
+#include <asm/asm.h>
+#include <asm/asm-offsets.h>
+#include <asm/csr.h>
+
+ .text
+ .altmacro
+ .option norelax
+
+ENTRY(__kvm_riscv_switch_to)
+ /* Save Host GPRs (except A0 and T0-T6) */
+ REG_S ra, (KVM_ARCH_HOST_RA)(a0)
+ REG_S sp, (KVM_ARCH_HOST_SP)(a0)
+ REG_S gp, (KVM_ARCH_HOST_GP)(a0)
+ REG_S tp, (KVM_ARCH_HOST_TP)(a0)
+ REG_S s0, (KVM_ARCH_HOST_S0)(a0)
+ REG_S s1, (KVM_ARCH_HOST_S1)(a0)
+ REG_S a1, (KVM_ARCH_HOST_A1)(a0)
+ REG_S a2, (KVM_ARCH_HOST_A2)(a0)
+ REG_S a3, (KVM_ARCH_HOST_A3)(a0)
+ REG_S a4, (KVM_ARCH_HOST_A4)(a0)
+ REG_S a5, (KVM_ARCH_HOST_A5)(a0)
+ REG_S a6, (KVM_ARCH_HOST_A6)(a0)
+ REG_S a7, (KVM_ARCH_HOST_A7)(a0)
+ REG_S s2, (KVM_ARCH_HOST_S2)(a0)
+ REG_S s3, (KVM_ARCH_HOST_S3)(a0)
+ REG_S s4, (KVM_ARCH_HOST_S4)(a0)
+ REG_S s5, (KVM_ARCH_HOST_S5)(a0)
+ REG_S s6, (KVM_ARCH_HOST_S6)(a0)
+ REG_S s7, (KVM_ARCH_HOST_S7)(a0)
+ REG_S s8, (KVM_ARCH_HOST_S8)(a0)
+ REG_S s9, (KVM_ARCH_HOST_S9)(a0)
+ REG_S s10, (KVM_ARCH_HOST_S10)(a0)
+ REG_S s11, (KVM_ARCH_HOST_S11)(a0)
+
+ /* Save Host and Restore Guest SSTATUS */
+ REG_L t0, (KVM_ARCH_GUEST_SSTATUS)(a0)
+ csrrw t0, CSR_SSTATUS, t0
+ REG_S t0, (KVM_ARCH_HOST_SSTATUS)(a0)
+
+ /* Save Host and Restore Guest HSTATUS */
+ REG_L t1, (KVM_ARCH_GUEST_HSTATUS)(a0)
+ csrrw t1, CSR_HSTATUS, t1
+ REG_S t1, (KVM_ARCH_HOST_HSTATUS)(a0)
+
+ /* Save Host and Restore Guest SCOUNTEREN */
+ REG_L t2, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
+ csrrw t2, CSR_SCOUNTEREN, t2
+ REG_S t2, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
+
+ /* Save Host SSCRATCH and change it to struct kvm_vcpu_arch pointer */
+ csrrw t3, CSR_SSCRATCH, a0
+ REG_S t3, (KVM_ARCH_HOST_SSCRATCH)(a0)
+
+ /* Save Host STVEC and change it to return path */
+ la t4, __kvm_switch_return
+ csrrw t4, CSR_STVEC, t4
+ REG_S t4, (KVM_ARCH_HOST_STVEC)(a0)
+
+ /* Restore Guest SEPC */
+ REG_L t0, (KVM_ARCH_GUEST_SEPC)(a0)
+ csrw CSR_SEPC, t0
+
+ /* Restore Guest GPRs (except A0) */
+ REG_L ra, (KVM_ARCH_GUEST_RA)(a0)
+ REG_L sp, (KVM_ARCH_GUEST_SP)(a0)
+ REG_L gp, (KVM_ARCH_GUEST_GP)(a0)
+ REG_L tp, (KVM_ARCH_GUEST_TP)(a0)
+ REG_L t0, (KVM_ARCH_GUEST_T0)(a0)
+ REG_L t1, (KVM_ARCH_GUEST_T1)(a0)
+ REG_L t2, (KVM_ARCH_GUEST_T2)(a0)
+ REG_L s0, (KVM_ARCH_GUEST_S0)(a0)
+ REG_L s1, (KVM_ARCH_GUEST_S1)(a0)
+ REG_L a1, (KVM_ARCH_GUEST_A1)(a0)
+ REG_L a2, (KVM_ARCH_GUEST_A2)(a0)
+ REG_L a3, (KVM_ARCH_GUEST_A3)(a0)
+ REG_L a4, (KVM_ARCH_GUEST_A4)(a0)
+ REG_L a5, (KVM_ARCH_GUEST_A5)(a0)
+ REG_L a6, (KVM_ARCH_GUEST_A6)(a0)
+ REG_L a7, (KVM_ARCH_GUEST_A7)(a0)
+ REG_L s2, (KVM_ARCH_GUEST_S2)(a0)
+ REG_L s3, (KVM_ARCH_GUEST_S3)(a0)
+ REG_L s4, (KVM_ARCH_GUEST_S4)(a0)
+ REG_L s5, (KVM_ARCH_GUEST_S5)(a0)
+ REG_L s6, (KVM_ARCH_GUEST_S6)(a0)
+ REG_L s7, (KVM_ARCH_GUEST_S7)(a0)
+ REG_L s8, (KVM_ARCH_GUEST_S8)(a0)
+ REG_L s9, (KVM_ARCH_GUEST_S9)(a0)
+ REG_L s10, (KVM_ARCH_GUEST_S10)(a0)
+ REG_L s11, (KVM_ARCH_GUEST_S11)(a0)
+ REG_L t3, (KVM_ARCH_GUEST_T3)(a0)
+ REG_L t4, (KVM_ARCH_GUEST_T4)(a0)
+ REG_L t5, (KVM_ARCH_GUEST_T5)(a0)
+ REG_L t6, (KVM_ARCH_GUEST_T6)(a0)
+
+ /* Restore Guest A0 */
+ REG_L a0, (KVM_ARCH_GUEST_A0)(a0)
+
+ /* Resume Guest */
+ sret
+
+ /* Back to Host */
+ .align 2
+__kvm_switch_return:
+ /* Swap Guest A0 with SSCRATCH */
+ csrrw a0, CSR_SSCRATCH, a0
+
+ /* Save Guest GPRs (except A0) */
+ REG_S ra, (KVM_ARCH_GUEST_RA)(a0)
+ REG_S sp, (KVM_ARCH_GUEST_SP)(a0)
+ REG_S gp, (KVM_ARCH_GUEST_GP)(a0)
+ REG_S tp, (KVM_ARCH_GUEST_TP)(a0)
+ REG_S t0, (KVM_ARCH_GUEST_T0)(a0)
+ REG_S t1, (KVM_ARCH_GUEST_T1)(a0)
+ REG_S t2, (KVM_ARCH_GUEST_T2)(a0)
+ REG_S s0, (KVM_ARCH_GUEST_S0)(a0)
+ REG_S s1, (KVM_ARCH_GUEST_S1)(a0)
+ REG_S a1, (KVM_ARCH_GUEST_A1)(a0)
+ REG_S a2, (KVM_ARCH_GUEST_A2)(a0)
+ REG_S a3, (KVM_ARCH_GUEST_A3)(a0)
+ REG_S a4, (KVM_ARCH_GUEST_A4)(a0)
+ REG_S a5, (KVM_ARCH_GUEST_A5)(a0)
+ REG_S a6, (KVM_ARCH_GUEST_A6)(a0)
+ REG_S a7, (KVM_ARCH_GUEST_A7)(a0)
+ REG_S s2, (KVM_ARCH_GUEST_S2)(a0)
+ REG_S s3, (KVM_ARCH_GUEST_S3)(a0)
+ REG_S s4, (KVM_ARCH_GUEST_S4)(a0)
+ REG_S s5, (KVM_ARCH_GUEST_S5)(a0)
+ REG_S s6, (KVM_ARCH_GUEST_S6)(a0)
+ REG_S s7, (KVM_ARCH_GUEST_S7)(a0)
+ REG_S s8, (KVM_ARCH_GUEST_S8)(a0)
+ REG_S s9, (KVM_ARCH_GUEST_S9)(a0)
+ REG_S s10, (KVM_ARCH_GUEST_S10)(a0)
+ REG_S s11, (KVM_ARCH_GUEST_S11)(a0)
+ REG_S t3, (KVM_ARCH_GUEST_T3)(a0)
+ REG_S t4, (KVM_ARCH_GUEST_T4)(a0)
+ REG_S t5, (KVM_ARCH_GUEST_T5)(a0)
+ REG_S t6, (KVM_ARCH_GUEST_T6)(a0)
+
+ /* Save Guest SEPC */
+ csrr t0, CSR_SEPC
+ REG_S t0, (KVM_ARCH_GUEST_SEPC)(a0)
+
+ /* Restore Host STVEC */
+ REG_L t1, (KVM_ARCH_HOST_STVEC)(a0)
+ csrw CSR_STVEC, t1
+
+ /* Save Guest A0 and Restore Host SSCRATCH */
+ REG_L t2, (KVM_ARCH_HOST_SSCRATCH)(a0)
+ csrrw t2, CSR_SSCRATCH, t2
+ REG_S t2, (KVM_ARCH_GUEST_A0)(a0)
+
+ /* Save Guest and Restore Host SCOUNTEREN */
+ REG_L t3, (KVM_ARCH_HOST_SCOUNTEREN)(a0)
+ csrrw t3, CSR_SCOUNTEREN, t3
+ REG_S t3, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)
+
+ /* Save Guest and Restore Host HSTATUS */
+ REG_L t4, (KVM_ARCH_HOST_HSTATUS)(a0)
+ csrrw t4, CSR_HSTATUS, t4
+ REG_S t4, (KVM_ARCH_GUEST_HSTATUS)(a0)
+
+ /* Save Guest and Restore Host SSTATUS */
+ REG_L t5, (KVM_ARCH_HOST_SSTATUS)(a0)
+ csrrw t5, CSR_SSTATUS, t5
+ REG_S t5, (KVM_ARCH_GUEST_SSTATUS)(a0)
+
+ /* Restore Host GPRs (except A0 and T0-T6) */
+ REG_L ra, (KVM_ARCH_HOST_RA)(a0)
+ REG_L sp, (KVM_ARCH_HOST_SP)(a0)
+ REG_L gp, (KVM_ARCH_HOST_GP)(a0)
+ REG_L tp, (KVM_ARCH_HOST_TP)(a0)
+ REG_L s0, (KVM_ARCH_HOST_S0)(a0)
+ REG_L s1, (KVM_ARCH_HOST_S1)(a0)
+ REG_L a1, (KVM_ARCH_HOST_A1)(a0)
+ REG_L a2, (KVM_ARCH_HOST_A2)(a0)
+ REG_L a3, (KVM_ARCH_HOST_A3)(a0)
+ REG_L a4, (KVM_ARCH_HOST_A4)(a0)
+ REG_L a5, (KVM_ARCH_HOST_A5)(a0)
+ REG_L a6, (KVM_ARCH_HOST_A6)(a0)
+ REG_L a7, (KVM_ARCH_HOST_A7)(a0)
+ REG_L s2, (KVM_ARCH_HOST_S2)(a0)
+ REG_L s3, (KVM_ARCH_HOST_S3)(a0)
+ REG_L s4, (KVM_ARCH_HOST_S4)(a0)
+ REG_L s5, (KVM_ARCH_HOST_S5)(a0)
+ REG_L s6, (KVM_ARCH_HOST_S6)(a0)
+ REG_L s7, (KVM_ARCH_HOST_S7)(a0)
+ REG_L s8, (KVM_ARCH_HOST_S8)(a0)
+ REG_L s9, (KVM_ARCH_HOST_S9)(a0)
+ REG_L s10, (KVM_ARCH_HOST_S10)(a0)
+ REG_L s11, (KVM_ARCH_HOST_S11)(a0)
+
+ /* Return to C code */
+ ret
+ENDPROC(__kvm_riscv_switch_to)
--
2.25.1

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