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Subject[PATCH 15/22] kvm: mmu: Support changed pte notifier in tdp MMU
From
In order to interoperate correctly with the rest of KVM and other Linux
subsystems, the TDP MMU must correctly handle various MMU notifiers. Add
a hook and handle the change_pte MMU notifier.

Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell
machine. This series introduced no new failures.

This series can be viewed in Gerrit at:
https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538

Signed-off-by: Ben Gardon <bgardon@google.com>
---
arch/x86/kvm/mmu/mmu.c | 46 +++++++++++++------------
arch/x86/kvm/mmu/mmu_internal.h | 13 +++++++
arch/x86/kvm/mmu/tdp_mmu.c | 61 +++++++++++++++++++++++++++++++++
arch/x86/kvm/mmu/tdp_mmu.h | 3 ++
4 files changed, 102 insertions(+), 21 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 8c1e806b3d53f..0d80abe82ca93 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -122,9 +122,6 @@ module_param(dbg, bool, 0644);

#define PTE_PREFETCH_NUM 8

-#define PT_FIRST_AVAIL_BITS_SHIFT 10
-#define PT64_SECOND_AVAIL_BITS_SHIFT 54
-
/*
* The mask used to denote special SPTEs, which can be either MMIO SPTEs or
* Access Tracking SPTEs.
@@ -147,13 +144,6 @@ module_param(dbg, bool, 0644);
#define PT32_INDEX(address, level)\
(((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1))

-
-#ifdef CONFIG_DYNAMIC_PHYSICAL_MASK
-#define PT64_BASE_ADDR_MASK (physical_mask & ~(u64)(PAGE_SIZE-1))
-#else
-#define PT64_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
-#endif
-
#define PT32_BASE_ADDR_MASK PAGE_MASK
#define PT32_DIR_BASE_ADDR_MASK \
(PAGE_MASK & ~((1ULL << (PAGE_SHIFT + PT32_LEVEL_BITS)) - 1))
@@ -170,9 +160,6 @@ module_param(dbg, bool, 0644);

#include <trace/events/kvm.h>

-#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
-#define SPTE_MMU_WRITEABLE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1))
-
/* make pte_list_desc fit well in cache line */
#define PTE_LIST_EXT 3

@@ -1708,6 +1695,21 @@ static int kvm_unmap_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
return kvm_zap_rmapp(kvm, rmap_head);
}

+u64 kvm_mmu_changed_pte_notifier_make_spte(u64 old_spte, kvm_pfn_t new_pfn)
+{
+ u64 new_spte;
+
+ new_spte = old_spte & ~PT64_BASE_ADDR_MASK;
+ new_spte |= (u64)new_pfn << PAGE_SHIFT;
+
+ new_spte &= ~PT_WRITABLE_MASK;
+ new_spte &= ~SPTE_HOST_WRITEABLE;
+
+ new_spte = mark_spte_for_access_track(new_spte);
+
+ return new_spte;
+}
+
static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
struct kvm_memory_slot *slot, gfn_t gfn, int level,
unsigned long data)
@@ -1733,13 +1735,8 @@ static int kvm_set_pte_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
pte_list_remove(rmap_head, sptep);
goto restart;
} else {
- new_spte = *sptep & ~PT64_BASE_ADDR_MASK;
- new_spte |= (u64)new_pfn << PAGE_SHIFT;
-
- new_spte &= ~PT_WRITABLE_MASK;
- new_spte &= ~SPTE_HOST_WRITEABLE;
-
- new_spte = mark_spte_for_access_track(new_spte);
+ new_spte = kvm_mmu_changed_pte_notifier_make_spte(
+ *sptep, new_pfn);

mmu_spte_clear_track_bits(sptep);
mmu_spte_set(sptep, new_spte);
@@ -1895,7 +1892,14 @@ int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end,

int kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte)
{
- return kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp);
+ int r;
+
+ r = kvm_handle_hva(kvm, hva, (unsigned long)&pte, kvm_set_pte_rmapp);
+
+ if (kvm->arch.tdp_mmu_enabled)
+ r |= kvm_tdp_mmu_set_spte_hva(kvm, hva, &pte);
+
+ return r;
}

static int kvm_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h
index 228bda0885552..8eaa6e4764bce 100644
--- a/arch/x86/kvm/mmu/mmu_internal.h
+++ b/arch/x86/kvm/mmu/mmu_internal.h
@@ -80,6 +80,12 @@ bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm,
(PT64_BASE_ADDR_MASK & ((1ULL << (PAGE_SHIFT + (((level) - 1) \
* PT64_LEVEL_BITS))) - 1))

+#ifdef CONFIG_DYNAMIC_PHYSICAL_MASK
+#define PT64_BASE_ADDR_MASK (physical_mask & ~(u64)(PAGE_SIZE-1))
+#else
+#define PT64_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
+#endif
+
extern u64 shadow_user_mask;
extern u64 shadow_accessed_mask;
extern u64 shadow_present_mask;
@@ -89,6 +95,12 @@ extern u64 shadow_present_mask;
#define ACC_USER_MASK PT_USER_MASK
#define ACC_ALL (ACC_EXEC_MASK | ACC_WRITE_MASK | ACC_USER_MASK)

+#define PT_FIRST_AVAIL_BITS_SHIFT 10
+#define PT64_SECOND_AVAIL_BITS_SHIFT 54
+
+#define SPTE_HOST_WRITEABLE (1ULL << PT_FIRST_AVAIL_BITS_SHIFT)
+#define SPTE_MMU_WRITEABLE (1ULL << (PT_FIRST_AVAIL_BITS_SHIFT + 1))
+
/* Functions for interpreting SPTEs */
kvm_pfn_t spte_to_pfn(u64 pte);
bool is_mmio_spte(u64 spte);
@@ -138,5 +150,6 @@ bool is_nx_huge_page_enabled(void);
void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc);

u64 mark_spte_for_access_track(u64 spte);
+u64 kvm_mmu_changed_pte_notifier_make_spte(u64 old_spte, kvm_pfn_t new_pfn);

#endif /* __KVM_X86_MMU_INTERNAL_H */
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 0a4b98669b3ef..3119583409131 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -722,3 +722,64 @@ int kvm_tdp_mmu_test_age_hva(struct kvm *kvm, unsigned long hva)
return kvm_tdp_mmu_handle_hva_range(kvm, hva, hva + 1, 0,
test_age_gfn);
}
+
+/*
+ * Handle the changed_pte MMU notifier for the TDP MMU.
+ * data is a pointer to the new pte_t mapping the HVA specified by the MMU
+ * notifier.
+ * Returns non-zero if a flush is needed before releasing the MMU lock.
+ */
+static int set_tdp_spte(struct kvm *kvm, struct kvm_memory_slot *slot,
+ struct kvm_mmu_page *root, gfn_t gfn, gfn_t unused,
+ unsigned long data)
+{
+ struct tdp_iter iter;
+ pte_t *ptep = (pte_t *)data;
+ kvm_pfn_t new_pfn;
+ u64 new_spte;
+ int need_flush = 0;
+ int as_id = kvm_mmu_page_as_id(root);
+
+ WARN_ON(pte_huge(*ptep));
+
+ new_pfn = pte_pfn(*ptep);
+
+ for_each_tdp_pte_root(iter, root, gfn, gfn + 1) {
+ if (iter.level != PG_LEVEL_4K)
+ continue;
+
+ if (!is_shadow_present_pte(iter.old_spte))
+ break;
+
+ *iter.sptep = 0;
+ handle_changed_spte(kvm, as_id, iter.gfn, iter.old_spte,
+ new_spte, iter.level);
+
+ kvm_flush_remote_tlbs_with_address(kvm, iter.gfn, 1);
+
+ if (!pte_write(*ptep)) {
+ new_spte = kvm_mmu_changed_pte_notifier_make_spte(
+ iter.old_spte, new_pfn);
+
+ *iter.sptep = new_spte;
+ handle_changed_spte(kvm, as_id, iter.gfn, iter.old_spte,
+ new_spte, iter.level);
+ }
+
+ need_flush = 1;
+ }
+
+ if (need_flush)
+ kvm_flush_remote_tlbs_with_address(kvm, gfn, 1);
+
+ return 0;
+}
+
+int kvm_tdp_mmu_set_spte_hva(struct kvm *kvm, unsigned long address,
+ pte_t *host_ptep)
+{
+ return kvm_tdp_mmu_handle_hva_range(kvm, address, address + 1,
+ (unsigned long)host_ptep,
+ set_tdp_spte);
+}
+
diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h
index f316773b7b5a8..5a399aa60b8d8 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.h
+++ b/arch/x86/kvm/mmu/tdp_mmu.h
@@ -25,4 +25,7 @@ int kvm_tdp_mmu_zap_hva_range(struct kvm *kvm, unsigned long start,
int kvm_tdp_mmu_age_hva_range(struct kvm *kvm, unsigned long start,
unsigned long end);
int kvm_tdp_mmu_test_age_hva(struct kvm *kvm, unsigned long hva);
+
+int kvm_tdp_mmu_set_spte_hva(struct kvm *kvm, unsigned long address,
+ pte_t *host_ptep);
#endif /* __KVM_X86_MMU_TDP_MMU_H */
--
2.28.0.709.gb0816b6eb0-goog
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