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RISC-V: KVM: Cache gstage pgd_levels in struct kvm_gstage

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Gstage page-table helpers frequently chase gstage->kvm->arch to
fetch pgd_levels. This adds noise and repeats the same dereference
chain in hot paths.

Add pgd_levels to struct kvm_gstage and initialize it from kvm->arch
when setting up a gstage instance. Introduce kvm_riscv_gstage_init()
to centralize initialization and switch gstage code to use
gstage->pgd_levels.

Suggested-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Fangyu Yu <fangyu.yu@linux.alibaba.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Nutty Liu <nutty.liu@hotmail.com>
Link: https://lore.kernel.org/r/20260403153019.9916-3-fangyu.yu@linux.alibaba.com
Signed-off-by: Anup Patel <anup@brainfault.org>
This commit is contained in:
Fangyu Yu 2026-04-03 23:30:17 +08:00 committed by Anup Patel
parent efcac8424b
commit ec92248431
3 changed files with 26 additions and 46 deletions
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10
arch/riscv/include/asm/kvm_gstage.h
View File

@ -15,6 +15,7 @@ struct kvm_gstage {
#define KVM_GSTAGE_FLAGS_LOCAL BIT(0)
unsigned long vmid;
pgd_t *pgd;
unsigned long pgd_levels;
};
struct kvm_gstage_mapping {
@ -96,4 +97,13 @@ static inline unsigned long kvm_riscv_gstage_mode(unsigned long pgd_levels)
}
}
static inline void kvm_riscv_gstage_init(struct kvm_gstage *gstage, struct kvm *kvm)
{
gstage->kvm = kvm;
gstage->flags = 0;
gstage->vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage->pgd = kvm->arch.pgd;
gstage->pgd_levels = kvm->arch.pgd_levels;
}
#endif

12
arch/riscv/kvm/gstage.c
View File

@ -26,7 +26,7 @@ static inline unsigned long gstage_pte_index(struct kvm_gstage *gstage,
unsigned long mask;
unsigned long shift = HGATP_PAGE_SHIFT + (kvm_riscv_gstage_index_bits * level);
if (level == gstage->kvm->arch.pgd_levels - 1)
if (level == gstage->pgd_levels - 1)
mask = (PTRS_PER_PTE * (1UL << kvm_riscv_gstage_pgd_xbits)) - 1;
else
mask = PTRS_PER_PTE - 1;
@ -45,7 +45,7 @@ static int gstage_page_size_to_level(struct kvm_gstage *gstage, unsigned long pa
u32 i;
unsigned long psz = 1UL << 12;
for (i = 0; i < gstage->kvm->arch.pgd_levels; i++) {
for (i = 0; i < gstage->pgd_levels; i++) {
if (page_size == (psz << (i * kvm_riscv_gstage_index_bits))) {
*out_level = i;
return 0;
@ -58,7 +58,7 @@ static int gstage_page_size_to_level(struct kvm_gstage *gstage, unsigned long pa
static int gstage_level_to_page_order(struct kvm_gstage *gstage, u32 level,
unsigned long *out_pgorder)
{
if (gstage->kvm->arch.pgd_levels < level)
if (gstage->pgd_levels < level)
return -EINVAL;
*out_pgorder = 12 + (level * kvm_riscv_gstage_index_bits);
@ -83,7 +83,7 @@ bool kvm_riscv_gstage_get_leaf(struct kvm_gstage *gstage, gpa_t addr,
pte_t **ptepp, u32 *ptep_level)
{
pte_t *ptep;
u32 current_level = gstage->kvm->arch.pgd_levels - 1;
u32 current_level = gstage->pgd_levels - 1;
*ptep_level = current_level;
ptep = (pte_t *)gstage->pgd;
@ -127,7 +127,7 @@ int kvm_riscv_gstage_set_pte(struct kvm_gstage *gstage,
struct kvm_mmu_memory_cache *pcache,
const struct kvm_gstage_mapping *map)
{
u32 current_level = gstage->kvm->arch.pgd_levels - 1;
u32 current_level = gstage->pgd_levels - 1;
pte_t *next_ptep = (pte_t *)gstage->pgd;
pte_t *ptep = &next_ptep[gstage_pte_index(gstage, map->addr, current_level)];
@ -288,7 +288,7 @@ int kvm_riscv_gstage_split_huge(struct kvm_gstage *gstage,
struct kvm_mmu_memory_cache *pcache,
gpa_t addr, u32 target_level, bool flush)
{
u32 current_level = gstage->kvm->arch.pgd_levels - 1;
u32 current_level = gstage->pgd_levels - 1;
pte_t *next_ptep = (pte_t *)gstage->pgd;
unsigned long huge_pte, child_pte;
unsigned long child_page_size;

50
arch/riscv/kvm/mmu.c
View File

@ -24,10 +24,7 @@ static void mmu_wp_memory_region(struct kvm *kvm, int slot)
phys_addr_t end = (memslot->base_gfn + memslot->npages) << PAGE_SHIFT;
struct kvm_gstage gstage;
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
spin_lock(&kvm->mmu_lock);
kvm_riscv_gstage_wp_range(&gstage, start, end);
@ -49,10 +46,7 @@ int kvm_riscv_mmu_ioremap(struct kvm *kvm, gpa_t gpa, phys_addr_t hpa,
struct kvm_gstage_mapping map;
struct kvm_gstage gstage;
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
end = (gpa + size + PAGE_SIZE - 1) & PAGE_MASK;
pfn = __phys_to_pfn(hpa);
@ -89,10 +83,7 @@ void kvm_riscv_mmu_iounmap(struct kvm *kvm, gpa_t gpa, unsigned long size)
{
struct kvm_gstage gstage;
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
spin_lock(&kvm->mmu_lock);
kvm_riscv_gstage_unmap_range(&gstage, gpa, size, false);
@ -109,10 +100,7 @@ void kvm_arch_mmu_enable_log_dirty_pt_masked(struct kvm *kvm,
phys_addr_t end = (base_gfn + __fls(mask) + 1) << PAGE_SHIFT;
struct kvm_gstage gstage;
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
kvm_riscv_gstage_wp_range(&gstage, start, end);
}
@ -141,10 +129,7 @@ void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
phys_addr_t size = slot->npages << PAGE_SHIFT;
struct kvm_gstage gstage;
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
spin_lock(&kvm->mmu_lock);
kvm_riscv_gstage_unmap_range(&gstage, gpa, size, false);
@ -250,10 +235,7 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
if (!kvm->arch.pgd)
return false;
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
mmu_locked = spin_trylock(&kvm->mmu_lock);
kvm_riscv_gstage_unmap_range(&gstage, range->start << PAGE_SHIFT,
(range->end - range->start) << PAGE_SHIFT,
@ -275,10 +257,7 @@ bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PUD_SIZE);
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
if (!kvm_riscv_gstage_get_leaf(&gstage, range->start << PAGE_SHIFT,
&ptep, &ptep_level))
return false;
@ -298,10 +277,7 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
WARN_ON(size != PAGE_SIZE && size != PMD_SIZE && size != PUD_SIZE);
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
if (!kvm_riscv_gstage_get_leaf(&gstage, range->start << PAGE_SHIFT,
&ptep, &ptep_level))
return false;
@ -463,10 +439,7 @@ int kvm_riscv_mmu_map(struct kvm_vcpu *vcpu, struct kvm_memory_slot *memslot,
struct kvm_gstage gstage;
struct page *page;
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
/* Setup initial state of output mapping */
memset(out_map, 0, sizeof(*out_map));
@ -587,10 +560,7 @@ void kvm_riscv_mmu_free_pgd(struct kvm *kvm)
spin_lock(&kvm->mmu_lock);
if (kvm->arch.pgd) {
gstage.kvm = kvm;
gstage.flags = 0;
gstage.vmid = READ_ONCE(kvm->arch.vmid.vmid);
gstage.pgd = kvm->arch.pgd;
kvm_riscv_gstage_init(&gstage, kvm);
kvm_riscv_gstage_unmap_range(&gstage, 0UL,
kvm_riscv_gstage_gpa_size(kvm->arch.pgd_levels), false);
pgd = READ_ONCE(kvm->arch.pgd);