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Message-ID: <CAAhSdy0d8mjr5-5Um2DpLgnhPb3UnGggXvbu_=oqEHWYzMP1SQ@mail.gmail.com>
Date: Mon, 29 Aug 2022 14:07:59 +0530
From: Anup Patel <anup@...infault.org>
To: Andrew Jones <ajones@...tanamicro.com>
Cc: linux-riscv@...ts.infradead.org, kvm-riscv@...ts.infradead.org,
linux-kernel@...r.kernel.org, paul.walmsley@...ive.com,
palmer@...belt.com, aou@...s.berkeley.edu,
mchitale@...tanamicro.com, heiko@...ech.de
Subject: Re: [PATCH 3/4] riscv: KVM: Apply insn-def to hfence encodings
On Fri, Aug 19, 2022 at 7:32 PM Andrew Jones <ajones@...tanamicro.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@...tanamicro.com>
> ---
> arch/riscv/include/asm/insn-def.h | 8 ++
> arch/riscv/kvm/tlb.c | 117 ++++--------------------------
> 2 files changed, 21 insertions(+), 104 deletions(-)
>
> diff --git a/arch/riscv/include/asm/insn-def.h b/arch/riscv/include/asm/insn-def.h
> index 4cd0208068dd..cd1c0d365f47 100644
> --- a/arch/riscv/include/asm/insn-def.h
> +++ b/arch/riscv/include/asm/insn-def.h
> @@ -79,4 +79,12 @@
> #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), vaddr, asid)
> +
> +#define HFENCE_GVMA(gaddr, vmid) \
> + INSN_R(OPCODE_SYSTEM, FUNC3(0), FUNC7(49), RD(0), gaddr, vmid)
> +
> #endif /* __ASM_INSN_DEF_H */
> diff --git a/arch/riscv/kvm/tlb.c b/arch/riscv/kvm/tlb.c
> index 1a76d0b1907d..f742a0d888e1 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,
> @@ -41,31 +26,14 @@ void kvm_riscv_local_hfence_gvma_vmid_gpa(unsigned long vmid,
> }
>
> 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");
> + asm volatile (HFENCE_GVMA("%0", "%1")
> + : : "r" (pos >> 2), "r" (vmid) : "memory");
You can drop the for-loop braces "{ }"
> }
> }
>
> 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,
> @@ -79,45 +47,16 @@ void kvm_riscv_local_hfence_gvma_gpa(gpa_t gpa, gpa_t gpsz,
> }
>
> 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");
> + asm volatile(HFENCE_GVMA("%0", "zero")
> + : : "r" (pos >> 2) : "memory");
You can drop the for-loop braces "{ }"
> }
> }
>
> 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,
> @@ -134,17 +73,8 @@ 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");
> + asm volatile(HFENCE_VVMA("%0", "%1")
> + : : "r" (pos), "r" (asid) : "memory");
You can drop the for-loop braces "{ }"
> }
>
> csr_write(CSR_HGATP, hgatp);
> @@ -157,15 +87,7 @@ 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);
> }
> @@ -184,15 +106,8 @@ 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");
> + asm volatile(HFENCE_VVMA("%0", "zero")
> + : : "r" (pos) : "memory");
> }
>
> csr_write(CSR_HGATP, hgatp);
> @@ -204,13 +119,7 @@ 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);
> }
> --
> 2.37.1
>
Apart from a few nits above, this looks good to me.
Reviewed-by: Anup Patel <anup@...infault.org>
Regards,
Anup
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