RISC-V: KVM: Add common nested acceleration support

Add a common nested acceleration support which will be shared by
all parts of KVM RISC-V. This nested acceleration support detects
and enables SBI NACL extension usage based on static keys which
ensures minimum impact on the non-nested scenario.

Signed-off-by: Anup Patel <apatel@ventanamicro.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20241020194734.58686-9-apatel@ventanamicro.com
Signed-off-by: Anup Patel <anup@brainfault.org>

1 files changed, 239 insertions, 0 deletions

diff --git a/arch/riscv/include/asm/kvm_nacl.h b/arch/riscv/include/asm/kvm_nacl.h
new file mode 100644
index 000000000000..8f3e3ebf5017
--- /dev/null
+++ b/arch/riscv/include/asm/kvm_nacl.h
@@ -0,0 +1,239 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2024 Ventana Micro Systems Inc.
+ */
+
+#ifndef __KVM_NACL_H
+#define __KVM_NACL_H
+
+#include <linux/jump_label.h>
+#include <linux/percpu.h>
+#include <asm/byteorder.h>
+#include <asm/csr.h>
+#include <asm/sbi.h>
+
+DECLARE_STATIC_KEY_FALSE(kvm_riscv_nacl_available);
+#define kvm_riscv_nacl_available() \
+	static_branch_unlikely(&kvm_riscv_nacl_available)
+
+DECLARE_STATIC_KEY_FALSE(kvm_riscv_nacl_sync_csr_available);
+#define kvm_riscv_nacl_sync_csr_available() \
+	static_branch_unlikely(&kvm_riscv_nacl_sync_csr_available)
+
+DECLARE_STATIC_KEY_FALSE(kvm_riscv_nacl_sync_hfence_available);
+#define kvm_riscv_nacl_sync_hfence_available() \
+	static_branch_unlikely(&kvm_riscv_nacl_sync_hfence_available)
+
+DECLARE_STATIC_KEY_FALSE(kvm_riscv_nacl_sync_sret_available);
+#define kvm_riscv_nacl_sync_sret_available() \
+	static_branch_unlikely(&kvm_riscv_nacl_sync_sret_available)
+
+DECLARE_STATIC_KEY_FALSE(kvm_riscv_nacl_autoswap_csr_available);
+#define kvm_riscv_nacl_autoswap_csr_available() \
+	static_branch_unlikely(&kvm_riscv_nacl_autoswap_csr_available)
+
+struct kvm_riscv_nacl {
+	void *shmem;
+	phys_addr_t shmem_phys;
+};
+DECLARE_PER_CPU(struct kvm_riscv_nacl, kvm_riscv_nacl);
+
+void __kvm_riscv_nacl_hfence(void *shmem,
+			     unsigned long control,
+			     unsigned long page_num,
+			     unsigned long page_count);
+
+int kvm_riscv_nacl_enable(void);
+
+void kvm_riscv_nacl_disable(void);
+
+void kvm_riscv_nacl_exit(void);
+
+int kvm_riscv_nacl_init(void);
+
+#ifdef CONFIG_32BIT
+#define lelong_to_cpu(__x)	le32_to_cpu(__x)
+#define cpu_to_lelong(__x)	cpu_to_le32(__x)
+#else
+#define lelong_to_cpu(__x)	le64_to_cpu(__x)
+#define cpu_to_lelong(__x)	cpu_to_le64(__x)
+#endif
+
+#define nacl_shmem()							\
+	this_cpu_ptr(&kvm_riscv_nacl)->shmem
+
+#define nacl_scratch_read_long(__shmem, __offset)			\
+({									\
+	unsigned long *__p = (__shmem) +				\
+			     SBI_NACL_SHMEM_SCRATCH_OFFSET +		\
+			     (__offset);				\
+	lelong_to_cpu(*__p);						\
+})
+
+#define nacl_scratch_write_long(__shmem, __offset, __val)		\
+do {									\
+	unsigned long *__p = (__shmem) +				\
+			     SBI_NACL_SHMEM_SCRATCH_OFFSET +		\
+			     (__offset);				\
+	*__p = cpu_to_lelong(__val);					\
+} while (0)
+
+#define nacl_scratch_write_longs(__shmem, __offset, __array, __count)	\
+do {									\
+	unsigned int __i;						\
+	unsigned long *__p = (__shmem) +				\
+			     SBI_NACL_SHMEM_SCRATCH_OFFSET +		\
+			     (__offset);				\
+	for (__i = 0; __i < (__count); __i++)				\
+		__p[__i] = cpu_to_lelong((__array)[__i]);		\
+} while (0)
+
+#define nacl_sync_hfence(__e)						\
+	sbi_ecall(SBI_EXT_NACL, SBI_EXT_NACL_SYNC_HFENCE,		\
+		  (__e), 0, 0, 0, 0, 0)
+
+#define nacl_hfence_mkconfig(__type, __order, __vmid, __asid)		\
+({									\
+	unsigned long __c = SBI_NACL_SHMEM_HFENCE_CONFIG_PEND;		\
+	__c |= ((__type) & SBI_NACL_SHMEM_HFENCE_CONFIG_TYPE_MASK)	\
+		<< SBI_NACL_SHMEM_HFENCE_CONFIG_TYPE_SHIFT;		\
+	__c |= (((__order) - SBI_NACL_SHMEM_HFENCE_ORDER_BASE) &	\
+		SBI_NACL_SHMEM_HFENCE_CONFIG_ORDER_MASK)		\
+		<< SBI_NACL_SHMEM_HFENCE_CONFIG_ORDER_SHIFT;		\
+	__c |= ((__vmid) & SBI_NACL_SHMEM_HFENCE_CONFIG_VMID_MASK)	\
+		<< SBI_NACL_SHMEM_HFENCE_CONFIG_VMID_SHIFT;		\
+	__c |= ((__asid) & SBI_NACL_SHMEM_HFENCE_CONFIG_ASID_MASK);	\
+	__c;								\
+})
+
+#define nacl_hfence_mkpnum(__order, __addr)				\
+	((__addr) >> (__order))
+
+#define nacl_hfence_mkpcount(__order, __size)				\
+	((__size) >> (__order))
+
+#define nacl_hfence_gvma(__shmem, __gpa, __gpsz, __order)		\
+__kvm_riscv_nacl_hfence(__shmem,					\
+	nacl_hfence_mkconfig(SBI_NACL_SHMEM_HFENCE_TYPE_GVMA,		\
+			   __order, 0, 0),				\
+	nacl_hfence_mkpnum(__order, __gpa),				\
+	nacl_hfence_mkpcount(__order, __gpsz))
+
+#define nacl_hfence_gvma_all(__shmem)					\
+__kvm_riscv_nacl_hfence(__shmem,					\
+	nacl_hfence_mkconfig(SBI_NACL_SHMEM_HFENCE_TYPE_GVMA_ALL,	\
+			   0, 0, 0), 0, 0)
+
+#define nacl_hfence_gvma_vmid(__shmem, __vmid, __gpa, __gpsz, __order)	\
+__kvm_riscv_nacl_hfence(__shmem,					\
+	nacl_hfence_mkconfig(SBI_NACL_SHMEM_HFENCE_TYPE_GVMA_VMID,	\
+			   __order, __vmid, 0),				\
+	nacl_hfence_mkpnum(__order, __gpa),				\
+	nacl_hfence_mkpcount(__order, __gpsz))
+
+#define nacl_hfence_gvma_vmid_all(__shmem, __vmid)			\
+__kvm_riscv_nacl_hfence(__shmem,					\
+	nacl_hfence_mkconfig(SBI_NACL_SHMEM_HFENCE_TYPE_GVMA_VMID_ALL,	\
+			   0, __vmid, 0), 0, 0)
+
+#define nacl_hfence_vvma(__shmem, __vmid, __gva, __gvsz, __order)	\
+__kvm_riscv_nacl_hfence(__shmem,					\
+	nacl_hfence_mkconfig(SBI_NACL_SHMEM_HFENCE_TYPE_VVMA,		\
+			   __order, __vmid, 0),				\
+	nacl_hfence_mkpnum(__order, __gva),				\
+	nacl_hfence_mkpcount(__order, __gvsz))
+
+#define nacl_hfence_vvma_all(__shmem, __vmid)				\
+__kvm_riscv_nacl_hfence(__shmem,					\
+	nacl_hfence_mkconfig(SBI_NACL_SHMEM_HFENCE_TYPE_VVMA_ALL,	\
+			   0, __vmid, 0), 0, 0)
+
+#define nacl_hfence_vvma_asid(__shmem, __vmid, __asid, __gva, __gvsz, __order)\
+__kvm_riscv_nacl_hfence(__shmem,					\
+	nacl_hfence_mkconfig(SBI_NACL_SHMEM_HFENCE_TYPE_VVMA_ASID,	\
+			   __order, __vmid, __asid),			\
+	nacl_hfence_mkpnum(__order, __gva),				\
+	nacl_hfence_mkpcount(__order, __gvsz))
+
+#define nacl_hfence_vvma_asid_all(__shmem, __vmid, __asid)		\
+__kvm_riscv_nacl_hfence(__shmem,					\
+	nacl_hfence_mkconfig(SBI_NACL_SHMEM_HFENCE_TYPE_VVMA_ASID_ALL,	\
+			   0, __vmid, __asid), 0, 0)
+
+#define nacl_csr_read(__shmem, __csr)					\
+({									\
+	unsigned long *__a = (__shmem) + SBI_NACL_SHMEM_CSR_OFFSET;	\
+	lelong_to_cpu(__a[SBI_NACL_SHMEM_CSR_INDEX(__csr)]);		\
+})
+
+#define nacl_csr_write(__shmem, __csr, __val)				\
+do {									\
+	void *__s = (__shmem);						\
+	unsigned int __i = SBI_NACL_SHMEM_CSR_INDEX(__csr);		\
+	unsigned long *__a = (__s) + SBI_NACL_SHMEM_CSR_OFFSET;		\
+	u8 *__b = (__s) + SBI_NACL_SHMEM_DBITMAP_OFFSET;		\
+	__a[__i] = cpu_to_lelong(__val);				\
+	__b[__i >> 3] |= 1U << (__i & 0x7);				\
+} while (0)
+
+#define nacl_csr_swap(__shmem, __csr, __val)				\
+({									\
+	void *__s = (__shmem);						\
+	unsigned int __i = SBI_NACL_SHMEM_CSR_INDEX(__csr);		\
+	unsigned long *__a = (__s) + SBI_NACL_SHMEM_CSR_OFFSET;		\
+	u8 *__b = (__s) + SBI_NACL_SHMEM_DBITMAP_OFFSET;		\
+	unsigned long __r = lelong_to_cpu(__a[__i]);			\
+	__a[__i] = cpu_to_lelong(__val);				\
+	__b[__i >> 3] |= 1U << (__i & 0x7);				\
+	__r;								\
+})
+
+#define nacl_sync_csr(__csr)						\
+	sbi_ecall(SBI_EXT_NACL, SBI_EXT_NACL_SYNC_CSR,			\
+		  (__csr), 0, 0, 0, 0, 0)
+
+/*
+ * Each ncsr_xyz() macro defined below has it's own static-branch so every
+ * use of ncsr_xyz() macro emits a patchable direct jump. This means multiple
+ * back-to-back ncsr_xyz() macro usage will emit multiple patchable direct
+ * jumps which is sub-optimal.
+ *
+ * Based on the above, it is recommended to avoid multiple back-to-back
+ * ncsr_xyz() macro usage.
+ */
+
+#define ncsr_read(__csr)						\
+({									\
+	unsigned long __r;						\
+	if (kvm_riscv_nacl_available())					\
+		__r = nacl_csr_read(nacl_shmem(), __csr);		\
+	else								\
+		__r = csr_read(__csr);					\
+	__r;								\
+})
+
+#define ncsr_write(__csr, __val)					\
+do {									\
+	if (kvm_riscv_nacl_sync_csr_available())			\
+		nacl_csr_write(nacl_shmem(), __csr, __val);		\
+	else								\
+		csr_write(__csr, __val);				\
+} while (0)
+
+#define ncsr_swap(__csr, __val)						\
+({									\
+	unsigned long __r;						\
+	if (kvm_riscv_nacl_sync_csr_available())			\
+		__r = nacl_csr_swap(nacl_shmem(), __csr, __val);	\
+	else								\
+		__r = csr_swap(__csr, __val);				\
+	__r;								\
+})
+
+#define nsync_csr(__csr)						\
+do {									\
+	if (kvm_riscv_nacl_sync_csr_available())			\
+		nacl_sync_csr(__csr);					\
+} while (0)
+
+#endif