RISC-V: KVM: Introduce range based local HFENCE functions

Various  __kvm_riscv_hfence_xyz() functions implemented in the
kvm/tlb.S are equivalent to corresponding HFENCE.GVMA instructions
and we don't have range based local HFENCE functions.

This patch provides complete set of local HFENCE functions which
supports range based TLB invalidation and supports HFENCE.VVMA
based functions. This is also a preparatory patch for upcoming
Svinval support in KVM RISC-V.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Anup Patel <anup@brainfault.org>

1 files changed, 213 insertions, 0 deletions

diff --git a/arch/riscv/kvm/tlb.c b/arch/riscv/kvm/tlb.c
new file mode 100644
index 000000000000..e2d4fd610745
--- /dev/null
+++ b/arch/riscv/kvm/tlb.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022 Ventana Micro Systems Inc.
+ */
+
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/kvm_host.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
+ */
+
+void kvm_riscv_local_hfence_gvma_vmid_gpa(unsigned long vmid,
+					  gpa_t gpa, gpa_t gpsz,
+					  unsigned long order)
+{
+	gpa_t pos;
+
+	if (PTRS_PER_PTE < (gpsz >> order)) {
+		kvm_riscv_local_hfence_gvma_vmid_all(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");
+	}
+}
+
+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");
+}
+
+void kvm_riscv_local_hfence_gvma_gpa(gpa_t gpa, gpa_t gpsz,
+				     unsigned long order)
+{
+	gpa_t pos;
+
+	if (PTRS_PER_PTE < (gpsz >> order)) {
+		kvm_riscv_local_hfence_gvma_all();
+		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");
+	}
+}
+
+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");
+}
+
+/*
+ * 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,
+					  unsigned long gvsz,
+					  unsigned long order)
+{
+	unsigned long pos, hgatp;
+
+	if (PTRS_PER_PTE < (gvsz >> order)) {
+		kvm_riscv_local_hfence_vvma_asid_all(vmid, asid);
+		return;
+	}
+
+	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");
+	}
+
+	csr_write(CSR_HGATP, hgatp);
+}
+
+void kvm_riscv_local_hfence_vvma_asid_all(unsigned long vmid,
+					  unsigned long asid)
+{
+	unsigned long hgatp;
+
+	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");
+
+	csr_write(CSR_HGATP, hgatp);
+}
+
+void kvm_riscv_local_hfence_vvma_gva(unsigned long vmid,
+				     unsigned long gva, unsigned long gvsz,
+				     unsigned long order)
+{
+	unsigned long pos, hgatp;
+
+	if (PTRS_PER_PTE < (gvsz >> order)) {
+		kvm_riscv_local_hfence_vvma_all(vmid);
+		return;
+	}
+
+	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");
+	}
+
+	csr_write(CSR_HGATP, hgatp);
+}
+
+void kvm_riscv_local_hfence_vvma_all(unsigned long vmid)
+{
+	unsigned long hgatp;
+
+	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");
+
+	csr_write(CSR_HGATP, hgatp);
+}