[PATCH 08/13] RISC-V: KVM: Add common nested acceleration support

Anup Patel
2024-07-19T16:09:53Z

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>
---
arch/riscv/include/asm/kvm_nacl.h | 205 ++++++++++++++++++++++++++++++
arch/riscv/kvm/Makefile | 1 +
arch/riscv/kvm/main.c | 53 +++++++-
arch/riscv/kvm/nacl.c | 152 ++++++++++++++++++++++
4 files changed, 409 insertions(+), 2 deletions(-)
create mode 100644 arch/riscv/include/asm/kvm_nacl.h
create mode 100644 arch/riscv/kvm/nacl.c

diff --git a/arch/riscv/include/asm/kvm_nacl.h b/arch/riscv/include/asm/kvm_nacl.h
new file mode 100644
index 000000000000..a704e8000a58
--- /dev/null
+++ b/arch/riscv/include/asm/kvm_nacl.h
@@ -0,0 +1,205 @@
+/* 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_shmem_fast() \
+ (kvm_riscv_nacl_available() ? nacl_shmem() : NULL)
+
+#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)
+
+#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
diff --git a/arch/riscv/kvm/Makefile b/arch/riscv/kvm/Makefile
index c1eac0d093de..0fb1840c3e0a 100644
--- a/arch/riscv/kvm/Makefile
+++ b/arch/riscv/kvm/Makefile
@@ -16,6 +16,7 @@ kvm-y += aia_device.o
kvm-y += aia_imsic.o
kvm-y += main.o
kvm-y += mmu.o
+kvm-y += nacl.o
kvm-y += tlb.o
kvm-y += vcpu.o
kvm-y += vcpu_exit.o
diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
index bab2ec34cd87..fd78f40bbb04 100644
--- a/arch/riscv/kvm/main.c
+++ b/arch/riscv/kvm/main.c
@@ -10,8 +10,8 @@
#include <linux/err.h>
#include <linux/module.h>
#include <linux/kvm_host.h>
-#include <asm/csr.h>
#include <asm/cpufeature.h>
+#include <asm/kvm_nacl.h>
#include <asm/sbi.h>

long kvm_arch_dev_ioctl(struct file *filp,
@@ -22,6 +22,12 @@ long kvm_arch_dev_ioctl(struct file *filp,

int kvm_arch_hardware_enable(void)
{
+ int rc;
+
+ rc = kvm_riscv_nacl_enable();
+ if (rc)
+ return rc;
+
csr_write(CSR_HEDELEG, KVM_HEDELEG_DEFAULT);
csr_write(CSR_HIDELEG, KVM_HIDELEG_DEFAULT);

@@ -49,11 +55,14 @@ void kvm_arch_hardware_disable(void)
csr_write(CSR_HVIP, 0);
csr_write(CSR_HEDELEG, 0);
csr_write(CSR_HIDELEG, 0);
+
+ kvm_riscv_nacl_disable();
}

static int __init riscv_kvm_init(void)
{
int rc;
+ char slist[64];
const char *str;

if (!riscv_isa_extension_available(NULL, h)) {
@@ -71,16 +80,53 @@ static int __init riscv_kvm_init(void)
return -ENODEV;
}

+ rc = kvm_riscv_nacl_init();
+ if (rc && rc != -ENODEV)
+ return rc;
+
kvm_riscv_gstage_mode_detect();

kvm_riscv_gstage_vmid_detect();

rc = kvm_riscv_aia_init();
- if (rc && rc != -ENODEV)
+ if (rc && rc != -ENODEV) {
+ kvm_riscv_nacl_exit();
return rc;
+ }

kvm_info("hypervisor extension available\n");

+ if (kvm_riscv_nacl_available()) {
+ rc = 0;
+ slist[0] = '\0';
+ if (kvm_riscv_nacl_sync_csr_available()) {
+ if (rc)
+ strcat(slist, ", ");
+ strcat(slist, "sync_csr");
+ rc++;
+ }
+ if (kvm_riscv_nacl_sync_hfence_available()) {
+ if (rc)
+ strcat(slist, ", ");
+ strcat(slist, "sync_hfence");
+ rc++;
+ }
+ if (kvm_riscv_nacl_sync_sret_available()) {
+ if (rc)
+ strcat(slist, ", ");
+ strcat(slist, "sync_sret");
+ rc++;
+ }
+ if (kvm_riscv_nacl_autoswap_csr_available()) {
+ if (rc)
+ strcat(slist, ", ");
+ strcat(slist, "autoswap_csr");
+ rc++;
+ }
+ kvm_info("using SBI nested acceleration with %s\n",
+ (rc) ? slist : "no features");
+ }
+
switch (kvm_riscv_gstage_mode()) {
case HGATP_MODE_SV32X4:
str = "Sv32x4";
@@ -108,6 +154,7 @@ static int __init riscv_kvm_init(void)
rc = kvm_init(sizeof(struct kvm_vcpu), 0, THIS_MODULE);
if (rc) {
kvm_riscv_aia_exit();
+ kvm_riscv_nacl_exit();
return rc;
}

@@ -119,6 +166,8 @@ static void __exit riscv_kvm_exit(void)
{
kvm_riscv_aia_exit();

+ kvm_riscv_nacl_exit();
+
kvm_exit();
}
module_exit(riscv_kvm_exit);
diff --git a/arch/riscv/kvm/nacl.c b/arch/riscv/kvm/nacl.c
new file mode 100644
index 000000000000..08a95ad9ada2
--- /dev/null
+++ b/arch/riscv/kvm/nacl.c
@@ -0,0 +1,152 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2024 Ventana Micro Systems Inc.
+ */
+
+#include <linux/kvm_host.h>
+#include <linux/vmalloc.h>
+#include <asm/kvm_nacl.h>
+
+DEFINE_STATIC_KEY_FALSE(kvm_riscv_nacl_available);
+DEFINE_STATIC_KEY_FALSE(kvm_riscv_nacl_sync_csr_available);
+DEFINE_STATIC_KEY_FALSE(kvm_riscv_nacl_sync_hfence_available);
+DEFINE_STATIC_KEY_FALSE(kvm_riscv_nacl_sync_sret_available);
+DEFINE_STATIC_KEY_FALSE(kvm_riscv_nacl_autoswap_csr_available);
+DEFINE_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 i, ent = -1, try_count = 5;
+ unsigned long *entp;
+
+again:
+ for (i = 0; i < SBI_NACL_SHMEM_HFENCE_ENTRY_MAX; i++) {
+ entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_CONFIG(i);
+ if (lelong_to_cpu(*entp) & SBI_NACL_SHMEM_HFENCE_CONFIG_PEND)
+ continue;
+
+ ent = i;
+ break;
+ }
+
+ if (ent < 0) {
+ if (try_count) {
+ nacl_sync_hfence(-1UL);
+ goto again;
+ } else {
+ pr_warn("KVM: No free entry in NACL shared memory\n");
+ return;
+ }
+ }
+
+ entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_CONFIG(i);
+ *entp = cpu_to_lelong(control);
+ entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_PNUM(i);
+ *entp = cpu_to_lelong(page_num);
+ entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_PCOUNT(i);
+ *entp = cpu_to_lelong(page_count);
+}
+
+int kvm_riscv_nacl_enable(void)
+{
+ int rc;
+ struct sbiret ret;
+ struct kvm_riscv_nacl *nacl;
+
+ if (!kvm_riscv_nacl_available())
+ return 0;
+ nacl = this_cpu_ptr(&kvm_riscv_nacl);
+
+ ret = sbi_ecall(SBI_EXT_NACL, SBI_EXT_NACL_SET_SHMEM,
+ nacl->shmem_phys, 0, 0, 0, 0, 0);
+ rc = sbi_err_map_linux_errno(ret.error);
+ if (rc)
+ return rc;
+
+ return 0;
+}
+
+void kvm_riscv_nacl_disable(void)
+{
+ if (!kvm_riscv_nacl_available())
+ return;
+
+ sbi_ecall(SBI_EXT_NACL, SBI_EXT_NACL_SET_SHMEM,
+ SBI_SHMEM_DISABLE, SBI_SHMEM_DISABLE, 0, 0, 0, 0);
+}
+
+void kvm_riscv_nacl_exit(void)
+{
+ int cpu;
+ struct kvm_riscv_nacl *nacl;
+
+ if (!kvm_riscv_nacl_available())
+ return;
+
+ /* Allocate per-CPU shared memory */
+ for_each_possible_cpu(cpu) {
+ nacl = per_cpu_ptr(&kvm_riscv_nacl, cpu);
+ if (!nacl->shmem)
+ continue;
+
+ free_pages((unsigned long)nacl->shmem,
+ get_order(SBI_NACL_SHMEM_SIZE));
+ nacl->shmem = NULL;
+ nacl->shmem_phys = 0;
+ }
+}
+
+static long nacl_probe_feature(long feature_id)
+{
+ struct sbiret ret;
+
+ if (!kvm_riscv_nacl_available())
+ return 0;
+
+ ret = sbi_ecall(SBI_EXT_NACL, SBI_EXT_NACL_PROBE_FEATURE,
+ feature_id, 0, 0, 0, 0, 0);
+ return ret.value;
+}
+
+int kvm_riscv_nacl_init(void)
+{
+ int cpu;
+ struct page *shmem_page;
+ struct kvm_riscv_nacl *nacl;
+
+ if (sbi_spec_version < sbi_mk_version(1, 0) ||
+ sbi_probe_extension(SBI_EXT_NACL) <= 0)
+ return -ENODEV;
+
+ /* Enable NACL support */
+ static_branch_enable(&kvm_riscv_nacl_available);
+
+ /* Probe NACL features */
+ if (nacl_probe_feature(SBI_NACL_FEAT_SYNC_CSR))
+ static_branch_enable(&kvm_riscv_nacl_sync_csr_available);
+ if (nacl_probe_feature(SBI_NACL_FEAT_SYNC_HFENCE))
+ static_branch_enable(&kvm_riscv_nacl_sync_hfence_available);
+ if (nacl_probe_feature(SBI_NACL_FEAT_SYNC_SRET))
+ static_branch_enable(&kvm_riscv_nacl_sync_sret_available);
+ if (nacl_probe_feature(SBI_NACL_FEAT_AUTOSWAP_CSR))
+ static_branch_enable(&kvm_riscv_nacl_autoswap_csr_available);
+
+ /* Allocate per-CPU shared memory */
+ for_each_possible_cpu(cpu) {
+ nacl = per_cpu_ptr(&kvm_riscv_nacl, cpu);
+
+ shmem_page = alloc_pages(GFP_KERNEL | __GFP_ZERO,
+ get_order(SBI_NACL_SHMEM_SIZE));
+ if (!shmem_page) {
+ kvm_riscv_nacl_exit();
+ return -ENOMEM;
+ }
+ nacl->shmem = page_to_virt(shmem_page);
+ nacl->shmem_phys = page_to_phys(shmem_page);
+ }
+
+ return 0;
+}
--
2.34.1