[RFC PATCH 14/37] KVM: MMU: Introduce common macros for TDP page tables

David Matlack
2022-12-08T19:46:38Z

Introduce macros in common KVM code for dealing with TDP page tables.
TDP page tables are assumed to be PAGE_SIZE with 64-bit PTEs. ARM will
have some nuance, e.g. for root page table concatenation, but that will
be handled separately when the time comes. Furthermore, we can add
arch-specific overrides for any of these macros in the future on a case
by case basis.

Signed-off-by: David Matlack <dmatlack@google.com>
---
arch/x86/kvm/mmu/tdp_iter.c | 14 +++++++-------
arch/x86/kvm/mmu/tdp_iter.h | 3 ++-
arch/x86/kvm/mmu/tdp_mmu.c | 24 +++++++++++++-----------
include/kvm/tdp_pgtable.h | 21 +++++++++++++++++++++
4 files changed, 43 insertions(+), 19 deletions(-)
create mode 100644 include/kvm/tdp_pgtable.h

diff --git a/arch/x86/kvm/mmu/tdp_iter.c b/arch/x86/kvm/mmu/tdp_iter.c
index 4a7d58bf81c4..d6328dac9cd3 100644
--- a/arch/x86/kvm/mmu/tdp_iter.c
+++ b/arch/x86/kvm/mmu/tdp_iter.c
@@ -10,14 +10,15 @@
*/
static void tdp_iter_refresh_sptep(struct tdp_iter *iter)
{
- iter->sptep = iter->pt_path[iter->level - 1] +
- SPTE_INDEX(iter->gfn << PAGE_SHIFT, iter->level);
+ int pte_index = TDP_PTE_INDEX(iter->gfn, iter->level);
+
+ iter->sptep = iter->pt_path[iter->level - 1] + pte_index;
iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep);
}

static gfn_t round_gfn_for_level(gfn_t gfn, int level)
{
- return gfn & -KVM_PAGES_PER_HPAGE(level);
+ return gfn & -TDP_PAGES_PER_LEVEL(level);
}

/*
@@ -46,7 +47,7 @@ void tdp_iter_start(struct tdp_iter *iter, struct kvm_mmu_page *root,
int root_level = root->role.level;

WARN_ON(root_level < 1);
- WARN_ON(root_level > PT64_ROOT_MAX_LEVEL);
+ WARN_ON(root_level > TDP_ROOT_MAX_LEVEL);

iter->next_last_level_gfn = next_last_level_gfn;
iter->root_level = root_level;
@@ -116,11 +117,10 @@ static bool try_step_side(struct tdp_iter *iter)
* Check if the iterator is already at the end of the current page
* table.
*/
- if (SPTE_INDEX(iter->gfn << PAGE_SHIFT, iter->level) ==
- (SPTE_ENT_PER_PAGE - 1))
+ if (TDP_PTE_INDEX(iter->gfn, iter->level) == (TDP_PTES_PER_PAGE - 1))
return false;

- iter->gfn += KVM_PAGES_PER_HPAGE(iter->level);
+ iter->gfn += TDP_PAGES_PER_LEVEL(iter->level);
iter->next_last_level_gfn = iter->gfn;
iter->sptep++;
iter->old_spte = kvm_tdp_mmu_read_spte(iter->sptep);
diff --git a/arch/x86/kvm/mmu/tdp_iter.h b/arch/x86/kvm/mmu/tdp_iter.h
index 892c078aab58..bfac83ab52db 100644
--- a/arch/x86/kvm/mmu/tdp_iter.h
+++ b/arch/x86/kvm/mmu/tdp_iter.h
@@ -4,6 +4,7 @@
#define __KVM_X86_MMU_TDP_ITER_H

#include <linux/kvm_host.h>
+#include <kvm/tdp_pgtable.h>

#include "mmu.h"
#include "spte.h"
@@ -68,7 +69,7 @@ struct tdp_iter {
*/
gfn_t yielded_gfn;
/* Pointers to the page tables traversed to reach the current SPTE */
- tdp_ptep_t pt_path[PT64_ROOT_MAX_LEVEL];
+ tdp_ptep_t pt_path[TDP_ROOT_MAX_LEVEL];
/* A pointer to the current SPTE */
tdp_ptep_t sptep;
/* The lowest GFN mapped by the current SPTE */
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index bce0566f2d94..a6d6e393c009 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -7,6 +7,8 @@
#include "tdp_mmu.h"
#include "spte.h"

+#include <kvm/tdp_pgtable.h>
+
#include <asm/cmpxchg.h>
#include <trace/events/kvm.h>

@@ -428,9 +430,9 @@ static void handle_removed_pt(struct kvm *kvm, tdp_ptep_t pt, bool shared)

tdp_mmu_unlink_sp(kvm, sp, shared);

- for (i = 0; i < SPTE_ENT_PER_PAGE; i++) {
+ for (i = 0; i < TDP_PTES_PER_PAGE; i++) {
tdp_ptep_t sptep = pt + i;
- gfn_t gfn = base_gfn + i * KVM_PAGES_PER_HPAGE(level);
+ gfn_t gfn = base_gfn + i * TDP_PAGES_PER_LEVEL(level);
u64 old_spte;

if (shared) {
@@ -525,9 +527,9 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
bool is_leaf = is_present && is_last_spte(new_spte, level);
bool pfn_changed = spte_to_pfn(old_spte) != spte_to_pfn(new_spte);

- WARN_ON(level > PT64_ROOT_MAX_LEVEL);
+ WARN_ON(level > TDP_ROOT_MAX_LEVEL);
WARN_ON(level < PG_LEVEL_PTE);
- WARN_ON(gfn & (KVM_PAGES_PER_HPAGE(level) - 1));
+ WARN_ON(gfn & (TDP_PAGES_PER_LEVEL(level) - 1));

/*
* If this warning were to trigger it would indicate that there was a
@@ -677,7 +679,7 @@ static inline int tdp_mmu_zap_spte_atomic(struct kvm *kvm,
return ret;

kvm_flush_remote_tlbs_with_address(kvm, iter->gfn,
- KVM_PAGES_PER_HPAGE(iter->level));
+ TDP_PAGES_PER_LEVEL(iter->level));

/*
* No other thread can overwrite the removed SPTE as they must either
@@ -1075,7 +1077,7 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu,
else if (is_shadow_present_pte(iter->old_spte) &&
!is_last_spte(iter->old_spte, iter->level))
kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
- KVM_PAGES_PER_HPAGE(iter->level + 1));
+ TDP_PAGES_PER_LEVEL(iter->level + 1));

/*
* If the page fault was caused by a write but the page is write
@@ -1355,7 +1357,7 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root,

rcu_read_lock();

- BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL);
+ BUG_ON(min_level > TDP_MAX_HUGEPAGE_LEVEL);

for_each_tdp_pte_min_level(iter, root, min_level, start, end) {
retry:
@@ -1469,7 +1471,7 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter,
* No need for atomics when writing to sp->spt since the page table has
* not been linked in yet and thus is not reachable from any other CPU.
*/
- for (i = 0; i < SPTE_ENT_PER_PAGE; i++)
+ for (i = 0; i < TDP_PTES_PER_PAGE; i++)
sp->spt[i] = make_huge_page_split_spte(kvm, huge_spte, sp->role, i);

/*
@@ -1489,7 +1491,7 @@ static int tdp_mmu_split_huge_page(struct kvm *kvm, struct tdp_iter *iter,
* are overwriting from the page stats. But we have to manually update
* the page stats with the new present child pages.
*/
- kvm_update_page_stats(kvm, level - 1, SPTE_ENT_PER_PAGE);
+ kvm_update_page_stats(kvm, level - 1, TDP_PTES_PER_PAGE);

out:
trace_kvm_mmu_split_huge_page(iter->gfn, huge_spte, level, ret);
@@ -1731,7 +1733,7 @@ static void zap_collapsible_spte_range(struct kvm *kvm,
if (tdp_mmu_iter_cond_resched(kvm, &iter, false, true))
continue;

- if (iter.level > KVM_MAX_HUGEPAGE_LEVEL ||
+ if (iter.level > TDP_MAX_HUGEPAGE_LEVEL ||
!is_shadow_present_pte(iter.old_spte))
continue;

@@ -1793,7 +1795,7 @@ static bool write_protect_gfn(struct kvm *kvm, struct kvm_mmu_page *root,
u64 new_spte;
bool spte_set = false;

- BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL);
+ BUG_ON(min_level > TDP_MAX_HUGEPAGE_LEVEL);

rcu_read_lock();

diff --git a/include/kvm/tdp_pgtable.h b/include/kvm/tdp_pgtable.h
new file mode 100644
index 000000000000..968be8d92350
--- /dev/null
+++ b/include/kvm/tdp_pgtable.h
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __KVM_TDP_PGTABLE_H
+#define __KVM_TDP_PGTABLE_H
+
+#include <linux/log2.h>
+#include <linux/mm_types.h>
+
+#define TDP_ROOT_MAX_LEVEL 5
+#define TDP_MAX_HUGEPAGE_LEVEL PG_LEVEL_PUD
+#define TDP_PTES_PER_PAGE (PAGE_SIZE / sizeof(u64))
+#define TDP_LEVEL_BITS ilog2(TDP_PTES_PER_PAGE)
+#define TDP_LEVEL_MASK ((1UL << TDP_LEVEL_BITS) - 1)
+
+#define TDP_LEVEL_SHIFT(level) (((level) - 1) * TDP_LEVEL_BITS)
+
+#define TDP_PAGES_PER_LEVEL(level) (1UL << TDP_LEVEL_SHIFT(level))
+
+#define TDP_PTE_INDEX(gfn, level) \
+ (((gfn) >> TDP_LEVEL_SHIFT(level)) & TDP_LEVEL_MASK)
+
+#endif /* !__KVM_TDP_PGTABLE_H */
--
2.39.0.rc1.256.g54fd8350bd-goog