Commit b6114a7e authored by Anup Patel's avatar Anup Patel Committed by Anup Patel
Browse files

RISC-V: KVM: Save/restore HSTATUS in C source 



We will be optimizing HSTATUS CSR access via shared memory setup
using the SBI nested acceleration extension. To facilitate this,
we first move HSTATUS save/restore in kvm_riscv_vcpu_enter_exit().

Signed-off-by: default avatarAnup Patel <apatel@ventanamicro.com>
Reviewed-by: default avatarAtish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20241020194734.58686-3-apatel@ventanamicro.com


Signed-off-by: default avatarAnup Patel <anup@brainfault.org>
parent e403a90a

arch/riscv/kvm/vcpu.c

+9 −0
Original line number Diff line number Diff line
@@ -727,9 +727,18 @@ static __always_inline void kvm_riscv_vcpu_swap_in_host_state(struct kvm_vcpu *v 
 */

static void noinstr kvm_riscv_vcpu_enter_exit(struct kvm_vcpu *vcpu)

{

	struct kvm_cpu_context *gcntx = &vcpu->arch.guest_context;

	struct kvm_cpu_context *hcntx = &vcpu->arch.host_context;



	kvm_riscv_vcpu_swap_in_guest_state(vcpu);

	guest_state_enter_irqoff();



	hcntx->hstatus = csr_swap(CSR_HSTATUS, gcntx->hstatus);



	__kvm_riscv_switch_to(&vcpu->arch);



	gcntx->hstatus = csr_swap(CSR_HSTATUS, hcntx->hstatus);



	vcpu->arch.last_exit_cpu = vcpu->cpu;

	guest_state_exit_irqoff();

	kvm_riscv_vcpu_swap_in_host_state(vcpu);

arch/riscv/kvm/vcpu_switch.S

+13 −23
Original line number Diff line number Diff line
@@ -43,35 +43,30 @@ SYM_FUNC_START(__kvm_riscv_switch_to) 


	/* Load Guest CSR values */

	REG_L	t0, (KVM_ARCH_GUEST_SSTATUS)(a0)

	REG_L	t1, (KVM_ARCH_GUEST_HSTATUS)(a0)

	REG_L	t2, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)

	la	t4, .Lkvm_switch_return

	REG_L	t5, (KVM_ARCH_GUEST_SEPC)(a0)

	REG_L	t1, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)

	la	t3, .Lkvm_switch_return

	REG_L	t4, (KVM_ARCH_GUEST_SEPC)(a0)



	/* Save Host and Restore Guest SSTATUS */

	csrrw	t0, CSR_SSTATUS, t0



	/* Save Host and Restore Guest HSTATUS */

	csrrw	t1, CSR_HSTATUS, t1



	/* Save Host and Restore Guest SCOUNTEREN */

	csrrw	t2, CSR_SCOUNTEREN, t2

	csrrw	t1, CSR_SCOUNTEREN, t1



	/* Save Host STVEC and change it to return path */

	csrrw	t4, CSR_STVEC, t4

	csrrw	t3, CSR_STVEC, t3



	/* Save Host SSCRATCH and change it to struct kvm_vcpu_arch pointer */

	csrrw	t3, CSR_SSCRATCH, a0

	csrrw	t2, CSR_SSCRATCH, a0



	/* Restore Guest SEPC */

	csrw	CSR_SEPC, t5

	csrw	CSR_SEPC, t4



	/* Store Host CSR values */

	REG_S	t0, (KVM_ARCH_HOST_SSTATUS)(a0)

	REG_S	t1, (KVM_ARCH_HOST_HSTATUS)(a0)

	REG_S	t2, (KVM_ARCH_HOST_SCOUNTEREN)(a0)

	REG_S	t3, (KVM_ARCH_HOST_SSCRATCH)(a0)

	REG_S	t4, (KVM_ARCH_HOST_STVEC)(a0)

	REG_S	t1, (KVM_ARCH_HOST_SCOUNTEREN)(a0)

	REG_S	t2, (KVM_ARCH_HOST_SSCRATCH)(a0)

	REG_S	t3, (KVM_ARCH_HOST_STVEC)(a0)



	/* Restore Guest GPRs (except A0) */

	REG_L	ra, (KVM_ARCH_GUEST_RA)(a0)
@@ -153,8 +148,7 @@ SYM_FUNC_START(__kvm_riscv_switch_to) 
	REG_L	t1, (KVM_ARCH_HOST_STVEC)(a0)

	REG_L	t2, (KVM_ARCH_HOST_SSCRATCH)(a0)

	REG_L	t3, (KVM_ARCH_HOST_SCOUNTEREN)(a0)

	REG_L	t4, (KVM_ARCH_HOST_HSTATUS)(a0)

	REG_L	t5, (KVM_ARCH_HOST_SSTATUS)(a0)

	REG_L	t4, (KVM_ARCH_HOST_SSTATUS)(a0)



	/* Save Guest SEPC */

	csrr	t0, CSR_SEPC
@@ -168,18 +162,14 @@ SYM_FUNC_START(__kvm_riscv_switch_to) 
	/* Save Guest and Restore Host SCOUNTEREN */

	csrrw	t3, CSR_SCOUNTEREN, t3



	/* Save Guest and Restore Host HSTATUS */

	csrrw	t4, CSR_HSTATUS, t4



	/* Save Guest and Restore Host SSTATUS */

	csrrw	t5, CSR_SSTATUS, t5

	csrrw	t4, CSR_SSTATUS, t4



	/* Store Guest CSR values */

	REG_S	t0, (KVM_ARCH_GUEST_SEPC)(a0)

	REG_S	t2, (KVM_ARCH_GUEST_A0)(a0)

	REG_S	t3, (KVM_ARCH_GUEST_SCOUNTEREN)(a0)

	REG_S	t4, (KVM_ARCH_GUEST_HSTATUS)(a0)

	REG_S	t5, (KVM_ARCH_GUEST_SSTATUS)(a0)

	REG_S	t4, (KVM_ARCH_GUEST_SSTATUS)(a0)



	/* Restore Host GPRs (except A0 and T0-T6) */

	REG_L	ra, (KVM_ARCH_HOST_RA)(a0)