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

[David Matlack <dmatlack@google.com>]

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