Re: [PATCH 10/13] RISC-V: KVM: Use nacl_csr_xyz() for accessing AIA CSRs

Atish Patra
2024-10-18T19:34:14Z

On Fri, Jul 19, 2024 at 9:10 AM Anup Patel <apatel@ventanamicro.com> wrote:
>
> When running under some other hypervisor, prefer nacl_csr_xyz()
> for accessing AIA CSRs in the run-loop. This makes CSR access
> faster whenever SBI nested acceleration is available.
>
> Signed-off-by: Anup Patel <apatel@ventanamicro.com>
> ---
> arch/riscv/kvm/aia.c | 97 ++++++++++++++++++++++++++++----------------
> 1 file changed, 63 insertions(+), 34 deletions(-)
>
> diff --git a/arch/riscv/kvm/aia.c b/arch/riscv/kvm/aia.c
> index 8ffae0330c89..dcced4db7fe8 100644
> --- a/arch/riscv/kvm/aia.c
> +++ b/arch/riscv/kvm/aia.c
> @@ -16,6 +16,7 @@
> #include <linux/percpu.h>
> #include <linux/spinlock.h>
> #include <asm/cpufeature.h>
> +#include <asm/kvm_nacl.h>
>
> struct aia_hgei_control {
> raw_spinlock_t lock;
> @@ -88,7 +89,7 @@ void kvm_riscv_vcpu_aia_sync_interrupts(struct kvm_vcpu *vcpu)
> struct kvm_vcpu_aia_csr *csr = &vcpu->arch.aia_context.guest_csr;
>
> if (kvm_riscv_aia_available())
> - csr->vsieh = csr_read(CSR_VSIEH);
> + csr->vsieh = ncsr_read(CSR_VSIEH);
> }
> #endif
>
> @@ -115,7 +116,7 @@ bool kvm_riscv_vcpu_aia_has_interrupts(struct kvm_vcpu *vcpu, u64 mask)
>
> hgei = aia_find_hgei(vcpu);
> if (hgei > 0)
> - return !!(csr_read(CSR_HGEIP) & BIT(hgei));
> + return !!(ncsr_read(CSR_HGEIP) & BIT(hgei));
>
> return false;
> }
> @@ -128,45 +129,73 @@ void kvm_riscv_vcpu_aia_update_hvip(struct kvm_vcpu *vcpu)
> return;
>
> #ifdef CONFIG_32BIT
> - csr_write(CSR_HVIPH, vcpu->arch.aia_context.guest_csr.hviph);
> + ncsr_write(CSR_HVIPH, vcpu->arch.aia_context.guest_csr.hviph);
> #endif
> - csr_write(CSR_HVICTL, aia_hvictl_value(!!(csr->hvip & BIT(IRQ_VS_EXT))));
> + ncsr_write(CSR_HVICTL, aia_hvictl_value(!!(csr->hvip & BIT(IRQ_VS_EXT))));
> }
>
> void kvm_riscv_vcpu_aia_load(struct kvm_vcpu *vcpu, int cpu)
> {
> struct kvm_vcpu_aia_csr *csr = &vcpu->arch.aia_context.guest_csr;
> + void *nsh;
>
> if (!kvm_riscv_aia_available())
> return;
>
> - csr_write(CSR_VSISELECT, csr->vsiselect);
> - csr_write(CSR_HVIPRIO1, csr->hviprio1);
> - csr_write(CSR_HVIPRIO2, csr->hviprio2);
> + if (kvm_riscv_nacl_sync_csr_available()) {
> + nsh = nacl_shmem();
> + nacl_csr_write(nsh, CSR_VSISELECT, csr->vsiselect);
> + nacl_csr_write(nsh, CSR_HVIPRIO1, csr->hviprio1);
> + nacl_csr_write(nsh, CSR_HVIPRIO2, csr->hviprio2);
> +#ifdef CONFIG_32BIT
> + nacl_csr_write(nsh, CSR_VSIEH, csr->vsieh);
> + nacl_csr_write(nsh, CSR_HVIPH, csr->hviph);
> + nacl_csr_write(nsh, CSR_HVIPRIO1H, csr->hviprio1h);
> + nacl_csr_write(nsh, CSR_HVIPRIO2H, csr->hviprio2h);
> +#endif
> + } else {
> + csr_write(CSR_VSISELECT, csr->vsiselect);
> + csr_write(CSR_HVIPRIO1, csr->hviprio1);
> + csr_write(CSR_HVIPRIO2, csr->hviprio2);
> #ifdef CONFIG_32BIT
> - csr_write(CSR_VSIEH, csr->vsieh);
> - csr_write(CSR_HVIPH, csr->hviph);
> - csr_write(CSR_HVIPRIO1H, csr->hviprio1h);
> - csr_write(CSR_HVIPRIO2H, csr->hviprio2h);
> + csr_write(CSR_VSIEH, csr->vsieh);
> + csr_write(CSR_HVIPH, csr->hviph);
> + csr_write(CSR_HVIPRIO1H, csr->hviprio1h);
> + csr_write(CSR_HVIPRIO2H, csr->hviprio2h);
> #endif
> + }
> }
>
> void kvm_riscv_vcpu_aia_put(struct kvm_vcpu *vcpu)
> {
> struct kvm_vcpu_aia_csr *csr = &vcpu->arch.aia_context.guest_csr;
> + void *nsh;
>
> if (!kvm_riscv_aia_available())
> return;
>
> - csr->vsiselect = csr_read(CSR_VSISELECT);
> - csr->hviprio1 = csr_read(CSR_HVIPRIO1);
> - csr->hviprio2 = csr_read(CSR_HVIPRIO2);
> + if (kvm_riscv_nacl_available()) {
> + nsh = nacl_shmem();
> + csr->vsiselect = nacl_csr_read(nsh, CSR_VSISELECT);
> + csr->hviprio1 = nacl_csr_read(nsh, CSR_HVIPRIO1);
> + csr->hviprio2 = nacl_csr_read(nsh, CSR_HVIPRIO2);
> #ifdef CONFIG_32BIT
> - csr->vsieh = csr_read(CSR_VSIEH);
> - csr->hviph = csr_read(CSR_HVIPH);
> - csr->hviprio1h = csr_read(CSR_HVIPRIO1H);
> - csr->hviprio2h = csr_read(CSR_HVIPRIO2H);
> + csr->vsieh = nacl_csr_read(nsh, CSR_VSIEH);
> + csr->hviph = nacl_csr_read(nsh, CSR_HVIPH);
> + csr->hviprio1h = nacl_csr_read(nsh, CSR_HVIPRIO1H);
> + csr->hviprio2h = nacl_csr_read(nsh, CSR_HVIPRIO2H);
> #endif
> + } else {
> + csr->vsiselect = csr_read(CSR_VSISELECT);
> + csr->hviprio1 = csr_read(CSR_HVIPRIO1);
> + csr->hviprio2 = csr_read(CSR_HVIPRIO2);
> +#ifdef CONFIG_32BIT
> + csr->vsieh = csr_read(CSR_VSIEH);
> + csr->hviph = csr_read(CSR_HVIPH);
> + csr->hviprio1h = csr_read(CSR_HVIPRIO1H);
> + csr->hviprio2h = csr_read(CSR_HVIPRIO2H);
> +#endif
> + }
> }
>
> int kvm_riscv_vcpu_aia_get_csr(struct kvm_vcpu *vcpu,
> @@ -250,20 +279,20 @@ static u8 aia_get_iprio8(struct kvm_vcpu *vcpu, unsigned int irq)
>
> switch (bitpos / BITS_PER_LONG) {
> case 0:
> - hviprio = csr_read(CSR_HVIPRIO1);
> + hviprio = ncsr_read(CSR_HVIPRIO1);
> break;
> case 1:
> #ifndef CONFIG_32BIT
> - hviprio = csr_read(CSR_HVIPRIO2);
> + hviprio = ncsr_read(CSR_HVIPRIO2);
> break;
> #else
> - hviprio = csr_read(CSR_HVIPRIO1H);
> + hviprio = ncsr_read(CSR_HVIPRIO1H);
> break;
> case 2:
> - hviprio = csr_read(CSR_HVIPRIO2);
> + hviprio = ncsr_read(CSR_HVIPRIO2);
> break;
> case 3:
> - hviprio = csr_read(CSR_HVIPRIO2H);
> + hviprio = ncsr_read(CSR_HVIPRIO2H);
> break;
> #endif
> default:
> @@ -283,20 +312,20 @@ static void aia_set_iprio8(struct kvm_vcpu *vcpu, unsigned int irq, u8 prio)
>
> switch (bitpos / BITS_PER_LONG) {
> case 0:
> - hviprio = csr_read(CSR_HVIPRIO1);
> + hviprio = ncsr_read(CSR_HVIPRIO1);
> break;
> case 1:
> #ifndef CONFIG_32BIT
> - hviprio = csr_read(CSR_HVIPRIO2);
> + hviprio = ncsr_read(CSR_HVIPRIO2);
> break;
> #else
> - hviprio = csr_read(CSR_HVIPRIO1H);
> + hviprio = ncsr_read(CSR_HVIPRIO1H);
> break;
> case 2:
> - hviprio = csr_read(CSR_HVIPRIO2);
> + hviprio = ncsr_read(CSR_HVIPRIO2);
> break;
> case 3:
> - hviprio = csr_read(CSR_HVIPRIO2H);
> + hviprio = ncsr_read(CSR_HVIPRIO2H);
> break;
> #endif
> default:
> @@ -308,20 +337,20 @@ static void aia_set_iprio8(struct kvm_vcpu *vcpu, unsigned int irq, u8 prio)
>
> switch (bitpos / BITS_PER_LONG) {
> case 0:
> - csr_write(CSR_HVIPRIO1, hviprio);
> + ncsr_write(CSR_HVIPRIO1, hviprio);
> break;
> case 1:
> #ifndef CONFIG_32BIT
> - csr_write(CSR_HVIPRIO2, hviprio);
> + ncsr_write(CSR_HVIPRIO2, hviprio);
> break;
> #else
> - csr_write(CSR_HVIPRIO1H, hviprio);
> + ncsr_write(CSR_HVIPRIO1H, hviprio);
> break;
> case 2:
> - csr_write(CSR_HVIPRIO2, hviprio);
> + ncsr_write(CSR_HVIPRIO2, hviprio);
> break;
> case 3:
> - csr_write(CSR_HVIPRIO2H, hviprio);
> + ncsr_write(CSR_HVIPRIO2H, hviprio);
> break;
> #endif
> default:
> @@ -377,7 +406,7 @@ int kvm_riscv_vcpu_aia_rmw_ireg(struct kvm_vcpu *vcpu, unsigned int csr_num,
> return KVM_INSN_ILLEGAL_TRAP;
>
> /* First try to emulate in kernel space */
> - isel = csr_read(CSR_VSISELECT) & ISELECT_MASK;
> + isel = ncsr_read(CSR_VSISELECT) & ISELECT_MASK;
> if (isel >= ISELECT_IPRIO0 && isel <= ISELECT_IPRIO15)
> return aia_rmw_iprio(vcpu, isel, val, new_val, wr_mask);
> else if (isel >= IMSIC_FIRST && isel <= IMSIC_LAST &&
> --
> 2.34.1
>

Reviewed-by: Atish Patra <atishp@rivosinc.com>

--
Regards,
Atish