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Message-ID: <CAOnJCUKMf4a0KQaiK5g8nAngqCKFtbnc38kQVu_nMb9ujwif1g@mail.gmail.com> Date: Wed, 16 Oct 2024 14:36:46 -0700 From: Atish Patra <atishp@...shpatra.org> To: Anup Patel <apatel@...tanamicro.com> Cc: Palmer Dabbelt <palmer@...belt.com>, Paul Walmsley <paul.walmsley@...ive.com>, Andrew Jones <ajones@...tanamicro.com>, Anup Patel <anup@...infault.org>, kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org, linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH 03/13] RISC-V: KVM: Save/restore SCOUNTEREN in C source On Fri, Jul 19, 2024 at 9:09 AM Anup Patel <apatel@...tanamicro.com> wrote: > > 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: Anup Patel <apatel@...tanamicro.com> > --- > arch/riscv/kvm/vcpu.c | 2 ++ > arch/riscv/kvm/vcpu_switch.S | 52 +++++++++++++++--------------------- > 2 files changed, 23 insertions(+), 31 deletions(-) > > diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c > index 93b1ce043482..957e1a5e081b 100644 > --- a/arch/riscv/kvm/vcpu.c > +++ b/arch/riscv/kvm/vcpu.c > @@ -691,6 +691,7 @@ 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)) > @@ -704,6 +705,7 @@ 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)) > diff --git a/arch/riscv/kvm/vcpu_switch.S b/arch/riscv/kvm/vcpu_switch.S > index f83643c4fdb9..3f8cbc21a644 100644 > --- a/arch/riscv/kvm/vcpu_switch.S > +++ b/arch/riscv/kvm/vcpu_switch.S > @@ -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) > -- > 2.34.1 > Reviewed-by: Atish Patra <atishp@...osinc.com> -- Regards, Atish
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