Re: [PATCH v2 3/4] riscv: KVM: Apply insn-def to hfence encodings

Anup Patel
2022-09-02T06:53:17Z

On Wed, Aug 31, 2022 at 10:55 PM Andrew Jones <ajones@ventanamicro.com> wrote:
>
> Introduce hfence instruction encodings and apply them to KVM's use.
> With the self-documenting nature of the instruction encoding macros,
> and a spec always within arm's reach, it's safe to remove the
> comments, so we do that too.
>
> Signed-off-by: Andrew Jones <ajones@ventanamicro.com>
> Reviewed-by: Anup Patel <anup@brainfault.org>

I have queued this patch for Linux-6.1

Thanks,
Anup

> ---
> arch/riscv/include/asm/insn-def.h | 10 +++
> arch/riscv/kvm/tlb.c | 129 ++++--------------------------
> 2 files changed, 27 insertions(+), 112 deletions(-)
>
> diff --git a/arch/riscv/include/asm/insn-def.h b/arch/riscv/include/asm/insn-def.h
> index 2dcd1d4781bf..86c1f602413b 100644
> --- a/arch/riscv/include/asm/insn-def.h
> +++ b/arch/riscv/include/asm/insn-def.h
> @@ -83,4 +83,14 @@
> #define __RS1(v) __REG(v)
> #define __RS2(v) __REG(v)
>
> +#define OPCODE_SYSTEM OPCODE(115)
> +
> +#define HFENCE_VVMA(vaddr, asid) \
> + INSN_R(OPCODE_SYSTEM, FUNC3(0), FUNC7(17), \
> + __RD(0), RS1(vaddr), RS2(asid))
> +
> +#define HFENCE_GVMA(gaddr, vmid) \
> + INSN_R(OPCODE_SYSTEM, FUNC3(0), FUNC7(49), \
> + __RD(0), RS1(gaddr), RS2(vmid))
> +
> #endif /* __ASM_INSN_DEF_H */
> diff --git a/arch/riscv/kvm/tlb.c b/arch/riscv/kvm/tlb.c
> index 1a76d0b1907d..1ce3394b3acf 100644
> --- a/arch/riscv/kvm/tlb.c
> +++ b/arch/riscv/kvm/tlb.c
> @@ -12,22 +12,7 @@
> #include <linux/kvm_host.h>
> #include <asm/cacheflush.h>
> #include <asm/csr.h>
> -
> -/*
> - * Instruction encoding of hfence.gvma is:
> - * HFENCE.GVMA rs1, rs2
> - * HFENCE.GVMA zero, rs2
> - * HFENCE.GVMA rs1
> - * HFENCE.GVMA
> - *
> - * rs1!=zero and rs2!=zero ==> HFENCE.GVMA rs1, rs2
> - * rs1==zero and rs2!=zero ==> HFENCE.GVMA zero, rs2
> - * rs1!=zero and rs2==zero ==> HFENCE.GVMA rs1
> - * rs1==zero and rs2==zero ==> HFENCE.GVMA
> - *
> - * Instruction encoding of HFENCE.GVMA is:
> - * 0110001 rs2(5) rs1(5) 000 00000 1110011
> - */
> +#include <asm/insn-def.h>
>
> void kvm_riscv_local_hfence_gvma_vmid_gpa(unsigned long vmid,
> gpa_t gpa, gpa_t gpsz,
> @@ -40,32 +25,14 @@ void kvm_riscv_local_hfence_gvma_vmid_gpa(unsigned long vmid,
> return;
> }
>
> - for (pos = gpa; pos < (gpa + gpsz); pos += BIT(order)) {
> - /*
> - * rs1 = a0 (GPA >> 2)
> - * rs2 = a1 (VMID)
> - * HFENCE.GVMA a0, a1
> - * 0110001 01011 01010 000 00000 1110011
> - */
> - asm volatile ("srli a0, %0, 2\n"
> - "add a1, %1, zero\n"
> - ".word 0x62b50073\n"
> - :: "r" (pos), "r" (vmid)
> - : "a0", "a1", "memory");
> - }
> + for (pos = gpa; pos < (gpa + gpsz); pos += BIT(order))
> + asm volatile (HFENCE_GVMA(%0, %1)
> + : : "r" (pos >> 2), "r" (vmid) : "memory");
> }
>
> void kvm_riscv_local_hfence_gvma_vmid_all(unsigned long vmid)
> {
> - /*
> - * rs1 = zero
> - * rs2 = a0 (VMID)
> - * HFENCE.GVMA zero, a0
> - * 0110001 01010 00000 000 00000 1110011
> - */
> - asm volatile ("add a0, %0, zero\n"
> - ".word 0x62a00073\n"
> - :: "r" (vmid) : "a0", "memory");
> + asm volatile(HFENCE_GVMA(zero, %0) : : "r" (vmid) : "memory");
> }
>
> void kvm_riscv_local_hfence_gvma_gpa(gpa_t gpa, gpa_t gpsz,
> @@ -78,46 +45,16 @@ void kvm_riscv_local_hfence_gvma_gpa(gpa_t gpa, gpa_t gpsz,
> return;
> }
>
> - for (pos = gpa; pos < (gpa + gpsz); pos += BIT(order)) {
> - /*
> - * rs1 = a0 (GPA >> 2)
> - * rs2 = zero
> - * HFENCE.GVMA a0
> - * 0110001 00000 01010 000 00000 1110011
> - */
> - asm volatile ("srli a0, %0, 2\n"
> - ".word 0x62050073\n"
> - :: "r" (pos) : "a0", "memory");
> - }
> + for (pos = gpa; pos < (gpa + gpsz); pos += BIT(order))
> + asm volatile(HFENCE_GVMA(%0, zero)
> + : : "r" (pos >> 2) : "memory");
> }
>
> void kvm_riscv_local_hfence_gvma_all(void)
> {
> - /*
> - * rs1 = zero
> - * rs2 = zero
> - * HFENCE.GVMA
> - * 0110001 00000 00000 000 00000 1110011
> - */
> - asm volatile (".word 0x62000073" ::: "memory");
> + asm volatile(HFENCE_GVMA(zero, zero) : : : "memory");
> }
>
> -/*
> - * Instruction encoding of hfence.gvma is:
> - * HFENCE.VVMA rs1, rs2
> - * HFENCE.VVMA zero, rs2
> - * HFENCE.VVMA rs1
> - * HFENCE.VVMA
> - *
> - * rs1!=zero and rs2!=zero ==> HFENCE.VVMA rs1, rs2
> - * rs1==zero and rs2!=zero ==> HFENCE.VVMA zero, rs2
> - * rs1!=zero and rs2==zero ==> HFENCE.VVMA rs1
> - * rs1==zero and rs2==zero ==> HFENCE.VVMA
> - *
> - * Instruction encoding of HFENCE.VVMA is:
> - * 0010001 rs2(5) rs1(5) 000 00000 1110011
> - */
> -
> void kvm_riscv_local_hfence_vvma_asid_gva(unsigned long vmid,
> unsigned long asid,
> unsigned long gva,
> @@ -133,19 +70,9 @@ void kvm_riscv_local_hfence_vvma_asid_gva(unsigned long vmid,
>
> hgatp = csr_swap(CSR_HGATP, vmid << HGATP_VMID_SHIFT);
>
> - for (pos = gva; pos < (gva + gvsz); pos += BIT(order)) {
> - /*
> - * rs1 = a0 (GVA)
> - * rs2 = a1 (ASID)
> - * HFENCE.VVMA a0, a1
> - * 0010001 01011 01010 000 00000 1110011
> - */
> - asm volatile ("add a0, %0, zero\n"
> - "add a1, %1, zero\n"
> - ".word 0x22b50073\n"
> - :: "r" (pos), "r" (asid)
> - : "a0", "a1", "memory");
> - }
> + for (pos = gva; pos < (gva + gvsz); pos += BIT(order))
> + asm volatile(HFENCE_VVMA(%0, %1)
> + : : "r" (pos), "r" (asid) : "memory");
>
> csr_write(CSR_HGATP, hgatp);
> }
> @@ -157,15 +84,7 @@ void kvm_riscv_local_hfence_vvma_asid_all(unsigned long vmid,
>
> hgatp = csr_swap(CSR_HGATP, vmid << HGATP_VMID_SHIFT);
>
> - /*
> - * rs1 = zero
> - * rs2 = a0 (ASID)
> - * HFENCE.VVMA zero, a0
> - * 0010001 01010 00000 000 00000 1110011
> - */
> - asm volatile ("add a0, %0, zero\n"
> - ".word 0x22a00073\n"
> - :: "r" (asid) : "a0", "memory");
> + asm volatile(HFENCE_VVMA(zero, %0) : : "r" (asid) : "memory");
>
> csr_write(CSR_HGATP, hgatp);
> }
> @@ -183,17 +102,9 @@ void kvm_riscv_local_hfence_vvma_gva(unsigned long vmid,
>
> hgatp = csr_swap(CSR_HGATP, vmid << HGATP_VMID_SHIFT);
>
> - for (pos = gva; pos < (gva + gvsz); pos += BIT(order)) {
> - /*
> - * rs1 = a0 (GVA)
> - * rs2 = zero
> - * HFENCE.VVMA a0
> - * 0010001 00000 01010 000 00000 1110011
> - */
> - asm volatile ("add a0, %0, zero\n"
> - ".word 0x22050073\n"
> - :: "r" (pos) : "a0", "memory");
> - }
> + for (pos = gva; pos < (gva + gvsz); pos += BIT(order))
> + asm volatile(HFENCE_VVMA(%0, zero)
> + : : "r" (pos) : "memory");
>
> csr_write(CSR_HGATP, hgatp);
> }
> @@ -204,13 +115,7 @@ void kvm_riscv_local_hfence_vvma_all(unsigned long vmid)
>
> hgatp = csr_swap(CSR_HGATP, vmid << HGATP_VMID_SHIFT);
>
> - /*
> - * rs1 = zero
> - * rs2 = zero
> - * HFENCE.VVMA
> - * 0010001 00000 00000 000 00000 1110011
> - */
> - asm volatile (".word 0x22000073" ::: "memory");
> + asm volatile(HFENCE_VVMA(zero, zero) : : : "memory");
>
> csr_write(CSR_HGATP, hgatp);
> }
> --
> 2.37.2