Commit b922307a authored by Anup Patel's avatar Anup Patel Committed by Anup Patel
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RISC-V: KVM: Save/restore SCOUNTEREN in C source 



The SCOUNTEREN CSR need not be saved/restored in the low-level
__kvm_riscv_switch_to() function hence move the SCOUNTEREN CSR
save/restore to the kvm_riscv_vcpu_swap_in_guest_state() and
kvm_riscv_vcpu_swap_in_host_state() functions in C sources.

Also, re-arrange the CSR save/restore and related GPR usage in
the low-level __kvm_riscv_switch_to() low-level function.

Signed-off-by: default avatarAnup Patel <apatel@ventanamicro.com>
Reviewed-by: default avatarAtish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20241020194734.58686-4-apatel@ventanamicro.com


Signed-off-by: default avatarAnup Patel <anup@brainfault.org>
parent b6114a7e

arch/riscv/kvm/vcpu.c

+2 −0
Original line number Diff line number Diff line
@@ -698,6 +698,7 @@ static __always_inline void kvm_riscv_vcpu_swap_in_guest_state(struct kvm_vcpu * 
	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;

	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;



	vcpu->arch.host_scounteren = csr_swap(CSR_SCOUNTEREN, csr->scounteren);

	vcpu->arch.host_senvcfg = csr_swap(CSR_SENVCFG, csr->senvcfg);

	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN) &&

	    (cfg->hstateen0 & SMSTATEEN0_SSTATEEN0))
@@ -711,6 +712,7 @@ static __always_inline void kvm_riscv_vcpu_swap_in_host_state(struct kvm_vcpu *v 
	struct kvm_vcpu_csr *csr = &vcpu->arch.guest_csr;

	struct kvm_vcpu_config *cfg = &vcpu->arch.cfg;



	csr->scounteren = csr_swap(CSR_SCOUNTEREN, vcpu->arch.host_scounteren);

	csr->senvcfg = csr_swap(CSR_SENVCFG, vcpu->arch.host_senvcfg);

	if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SMSTATEEN) &&

	    (cfg->hstateen0 & SMSTATEEN0_SSTATEEN0))

arch/riscv/kvm/vcpu_switch.S

+21 −31
Original line number Diff line number Diff line
@@ -43,30 +43,25 @@ 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_SCOUNTEREN)(a0)

	la	t3, .Lkvm_switch_return

	REG_L	t4, (KVM_ARCH_GUEST_SEPC)(a0)

	la	t1, .Lkvm_switch_return

	REG_L	t2, (KVM_ARCH_GUEST_SEPC)(a0)



	/* Save Host and Restore Guest SSTATUS */

	csrrw	t0, CSR_SSTATUS, t0



	/* Save Host and Restore Guest SCOUNTEREN */

	csrrw	t1, CSR_SCOUNTEREN, t1



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

	csrrw	t3, CSR_STVEC, t3



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

	csrrw	t2, CSR_SSCRATCH, a0

	csrrw	t1, CSR_STVEC, t1



	/* Restore Guest SEPC */

	csrw	CSR_SEPC, t4

	csrw	CSR_SEPC, t2



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

	csrrw	t3, CSR_SSCRATCH, a0



	/* Store Host CSR values */

	REG_S	t0, (KVM_ARCH_HOST_SSTATUS)(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)

	REG_S	t1, (KVM_ARCH_HOST_STVEC)(a0)

	REG_S	t3, (KVM_ARCH_HOST_SSCRATCH)(a0)



	/* Restore Guest GPRs (except A0) */

	REG_L	ra, (KVM_ARCH_GUEST_RA)(a0)
@@ -145,31 +140,26 @@ SYM_FUNC_START(__kvm_riscv_switch_to) 
	REG_S	t6, (KVM_ARCH_GUEST_T6)(a0)



	/* Load Host CSR values */

	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_SSTATUS)(a0)



	/* Save Guest SEPC */

	csrr	t0, CSR_SEPC

	REG_L	t0, (KVM_ARCH_HOST_STVEC)(a0)

	REG_L	t1, (KVM_ARCH_HOST_SSCRATCH)(a0)

	REG_L	t2, (KVM_ARCH_HOST_SSTATUS)(a0)



	/* Save Guest A0 and Restore Host SSCRATCH */

	csrrw	t2, CSR_SSCRATCH, t2

	csrrw	t1, CSR_SSCRATCH, t1



	/* Restore Host STVEC */

	csrw	CSR_STVEC, t1

	/* Save Guest SEPC */

	csrr	t3, CSR_SEPC



	/* Save Guest and Restore Host SCOUNTEREN */

	csrrw	t3, CSR_SCOUNTEREN, t3

	/* Restore Host STVEC */

	csrw	CSR_STVEC, t0



	/* Save Guest and Restore Host SSTATUS */

	csrrw	t4, CSR_SSTATUS, t4

	csrrw	t2, CSR_SSTATUS, t2



	/* 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_SSTATUS)(a0)

	REG_S	t1, (KVM_ARCH_GUEST_A0)(a0)

	REG_S	t2, (KVM_ARCH_GUEST_SSTATUS)(a0)

	REG_S	t3, (KVM_ARCH_GUEST_SEPC)(a0)



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

	REG_L	ra, (KVM_ARCH_HOST_RA)(a0)