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From:   Andrew Jones <ajones@ventanamicro.com>
To:     linux-riscv@lists.infradead.org, kvm-riscv@lists.infradead.org
Cc:     linux-kernel@vger.kernel.org, paul.walmsley@sifive.com,
        palmer@dabbelt.com, aou@eecs.berkeley.edu, anup@brainfault.org,
        mchitale@ventanamicro.com, heiko@sntech.de
Subject: [PATCH v2 3/4] riscv: KVM: Apply insn-def to hfence encodings
Date:   Wed, 31 Aug 2022 19:24:59 +0200
Message-Id: <20220831172500.752195-4-ajones@ventanamicro.com>
In-Reply-To: <20220831172500.752195-1-ajones@ventanamicro.com>
References: <20220831172500.752195-1-ajones@ventanamicro.com>
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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>
---
 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