Introduce alloc() and free() functions to the generic page-table code
for guest stage-2 page-tables and plumb these into the existing KVM
page-table allocator. Subsequent patches will convert other operations
within the KVM allocator over to the generic code.
Cc: Marc Zyngier <maz@xxxxxxxxxx>
Cc: Quentin Perret <qperret@xxxxxxxxxx>
Signed-off-by: Will Deacon <will@xxxxxxxxxx>
---
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/include/asm/kvm_pgtable.h | 17 ++++++++
arch/arm64/kvm/mmu.c | 42 ++++++++------------
arch/arm64/kvm/pgtable.c | 58 ++++++++++++++++++++++++++++
4 files changed, 93 insertions(+), 25 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index e1a32c0707bb..072ab1fac98a 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -81,6 +81,7 @@ struct kvm_s2_mmu {
*/
pgd_t *pgd;
phys_addr_t pgd_phys;
+ void *pgt_cookie;
/* The last vcpu id that ran on each physical CPU */
int __percpu *last_vcpu_ran;
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index c607025e1a05..7b4df5d0d2b8 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -99,6 +99,23 @@ void kvm_pgtable_hyp_free_cookie(void *cookie);
int kvm_pgtable_hyp_map(void *cookie, u64 addr, u64 size, u64 phys,
enum kvm_pgtable_prot prot);
+/**
+ * kvm_pgtable_stage2_alloc_cookie() - Allocate a guest stage-2 page-table.
+ * @kvm: KVM structure representing the guest virtual machine.
+ *
+ * Return: An opaque cookie which can be used to manipulate the page-table.
+ */
+void *kvm_pgtable_stage2_alloc_cookie(struct kvm *kvm);
+
+/**
+ * kvm_pgtable_stage2_free_cookie() - Free an unused guest stage-2 page-table.
+ * @cookie: Opaque cookie allocated by kvm_pgtable_stage2_alloc_cookie().
+ *
+ * The page-table is assumed to be unreachable by any hardware walkers prior
+ * to freeing and therefore no TLB invalidation is performed.
+ */
+void kvm_pgtable_stage2_free_cookie(void *cookie);
+
/**
* kvm_pgtable_get_pgd_phys() - Get physical pgd pointer for a page-table.
* @cookie: Opaque cookie allocated by kvm_pgtable_*_alloc_cookie().
diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index d5cb88a3c1e5..ecca611f208b 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -696,35 +696,27 @@ int create_hyp_exec_mappings(phys_addr_t phys_addr, size_t size,
* @kvm: The pointer to the KVM structure
* @mmu: The pointer to the s2 MMU structure
*
- * Allocates only the stage-2 HW PGD level table(s) of size defined by
- * stage2_pgd_size(mmu->kvm).
- *
+ * Allocates only the stage-2 HW PGD level table(s).
* Note we don't need locking here as this is only called when the VM is
* created, which can only be done once.
*/
int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
{
- phys_addr_t pgd_phys;
- pgd_t *pgd;
int cpu;
+ void *cookie;
- if (mmu->pgd != NULL) {
+ if (mmu->pgt_cookie != NULL) {
kvm_err("kvm_arch already initialized?\n");
return -EINVAL;
}
- /* Allocate the HW PGD, making sure that each page gets its own refcount */
- pgd = alloc_pages_exact(stage2_pgd_size(kvm), GFP_KERNEL | __GFP_ZERO);
- if (!pgd)
+ cookie = kvm_pgtable_stage2_alloc_cookie(kvm);
+ if (!cookie)
return -ENOMEM;
- pgd_phys = virt_to_phys(pgd);
- if (WARN_ON(pgd_phys & ~kvm_vttbr_baddr_mask(kvm)))
- return -EINVAL;
-
mmu->last_vcpu_ran = alloc_percpu(typeof(*mmu->last_vcpu_ran));
if (!mmu->last_vcpu_ran) {
- free_pages_exact(pgd, stage2_pgd_size(kvm));
+ kvm_pgtable_stage2_free_cookie(cookie);
return -ENOMEM;
}
@@ -732,8 +724,9 @@ int kvm_init_stage2_mmu(struct kvm *kvm, struct kvm_s2_mmu *mmu)
*per_cpu_ptr(mmu->last_vcpu_ran, cpu) = -1;
mmu->kvm = kvm;
- mmu->pgd = pgd;
- mmu->pgd_phys = pgd_phys;
+ mmu->pgt_cookie = cookie;
+ mmu->pgd_phys = kvm_pgtable_get_pgd_phys(cookie);
+ mmu->pgd = __va(mmu->pgd_phys);
mmu->vmid.vmid_gen = 0;
return 0;
@@ -809,21 +802,20 @@ void stage2_unmap_vm(struct kvm *kvm)
void kvm_free_stage2_pgd(struct kvm_s2_mmu *mmu)
{
struct kvm *kvm = mmu->kvm;
- void *pgd = NULL;
+ void *cookie = NULL;
spin_lock(&kvm->mmu_lock);
- if (mmu->pgd) {
- unmap_stage2_range(mmu, 0, kvm_phys_size(kvm));
- pgd = READ_ONCE(mmu->pgd);
+ cookie = mmu->pgt_cookie;
+ if (cookie) {
mmu->pgd = NULL;
+ mmu->pgd_phys = 0;
+ mmu->pgt_cookie = NULL;
+ free_percpu(mmu->last_vcpu_ran);
}
spin_unlock(&kvm->mmu_lock);
- /* Free the HW pgd, one page at a time */
- if (pgd) {
- free_pages_exact(pgd, stage2_pgd_size(kvm));
- free_percpu(mmu->last_vcpu_ran);
- }
+ if (cookie)
+ kvm_pgtable_stage2_free_cookie(cookie);
}
static p4d_t *stage2_get_p4d(struct kvm_s2_mmu *mmu, struct kvm_mmu_memory_cache *cache,
diff --git a/arch/arm64/kvm/pgtable.c b/arch/arm64/kvm/pgtable.c
index b148c76f8b79..f05a45c02361 100644
--- a/arch/arm64/kvm/pgtable.c
+++ b/arch/arm64/kvm/pgtable.c
@@ -443,3 +443,61 @@ u64 kvm_pgtable_get_pgd_phys(void *cookie)
struct kvm_pgtable *pgt = cookie;
return __pa(pgt->pgd);
}
+
+void *kvm_pgtable_stage2_alloc_cookie(struct kvm *kvm)
+{
+ size_t pgd_sz;
+ u64 vtcr = kvm->arch.vtcr;
+ struct kvm_pgtable *pgt = kzalloc(sizeof(*pgt), GFP_KERNEL);
+
+ if (!pgt)
+ return NULL;
+
+ pgt->ia_bits = VTCR_EL2_IPA(vtcr);
+ pgt->start_level = FIELD_GET(VTCR_EL2_SL0_MASK, vtcr);
+ pgt->mmu = &kvm->arch.mmu;
+
+ pgd_sz = kvm_pgd_pages(pgt) * PAGE_SIZE;
+ pgt->pgd = alloc_pages_exact(pgd_sz, GFP_KERNEL | __GFP_ZERO);
+ if (!pgt->pgd) {
+ kfree(pgt);
+ pgt = NULL;
+ }
+
+ return pgt;
+}
+
+static int stage2_free_walker(u64 addr, u64 end, u32 level, kvm_pte_t *ptep,
+ enum kvm_pgtable_walk_flags flag,
+ void * const arg)
+{
+ kvm_pte_t pte = *ptep;
+
+ if (!kvm_pte_valid(pte))
+ return 0;
+
+ put_page(virt_to_page(ptep));
+
+ if (kvm_pte_table(pte, level))
+ free_page((unsigned long)kvm_pte_follow(pte));
+
+ return 0;
+}
+
+void kvm_pgtable_stage2_free_cookie(void *cookie)
+{
+ size_t pgd_sz;
+ struct kvm_pgtable *pgt = cookie;
+ struct kvm_pgtable_walker walker = {
+ .cb = stage2_free_walker,
+ .flags = KVM_PGTABLE_WALK_LEAF |
+ KVM_PGTABLE_WALK_TABLE_POST,
+ };
+
+ if (kvm_pgtable_walk(cookie, 0, BIT(pgt->ia_bits), &walker))
+ kvm_err("Failed to free page-table pages\n");
+
+ pgd_sz = kvm_pgd_pages(pgt) * PAGE_SIZE;
+ free_pages_exact(pgt->pgd, pgd_sz);
+ kfree(pgt);
+}
--
2.28.0.rc0.142.g3c755180ce-goog
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