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// 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;
__lelong *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;
}
}
/*
* Per SBI v3.0 section 15.1.2, the Page_Number and Page_Count
* words must be updated before the Config word with its Pending
* bit set. WRITE_ONCE() stops the compiler from reordering the
* stores and smp_wmb() makes the parameter words globally
* visible to the SBI implementation (or NACL hardware) before
* the Pending bit is set.
*/
entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_PNUM(i);
WRITE_ONCE(*entp, cpu_to_lelong(page_num));
entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_PCOUNT(i);
WRITE_ONCE(*entp, cpu_to_lelong(page_count));
/* Ensure the parameter words are visible before the Pending bit */
smp_wmb();
entp = shmem + SBI_NACL_SHMEM_HFENCE_ENTRY_CONFIG(i);
WRITE_ONCE(*entp, cpu_to_lelong(control));
}
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;
}
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