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KVM: x86/mmu: Plumb a @can_yield parameter into __walk_slot_rmaps()

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Add a @can_yield param to __walk_slot_rmaps() to control whether or not
dropping mmu_lock and conditionally rescheduling is allowed.  This will
allow using __walk_slot_rmaps() and thus cond_resched() to handle
mmu_notifier invalidations, which usually allow blocking/yielding, but not
when invoked by the OOM killer.

Link: https://lore.kernel.org/r/20240809194335.1726916-12-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2024-08-09 12:43:23 -07:00
parent 0a37fffda1
commit 5b1fb116e1
1 changed files with 8 additions and 4 deletions
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12
arch/x86/kvm/mmu/mmu.c
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@@ -1526,7 +1526,8 @@ static __always_inline bool __walk_slot_rmaps(struct kvm *kvm,
slot_rmaps_handler fn,
int start_level, int end_level,
gfn_t start_gfn, gfn_t end_gfn,
bool flush_on_yield, bool flush)
bool can_yield, bool flush_on_yield,
bool flush)
{
struct slot_rmap_walk_iterator iterator;
@@ -1537,6 +1538,9 @@ static __always_inline bool __walk_slot_rmaps(struct kvm *kvm,
if (iterator.rmap)
flush |= fn(kvm, iterator.rmap, slot);
if (!can_yield)
continue;
if (need_resched() || rwlock_needbreak(&kvm->mmu_lock)) {
if (flush && flush_on_yield) {
kvm_flush_remote_tlbs_range(kvm, start_gfn,
@@ -1558,7 +1562,7 @@ static __always_inline bool walk_slot_rmaps(struct kvm *kvm,
{
return __walk_slot_rmaps(kvm, slot, fn, start_level, end_level,
slot->base_gfn, slot->base_gfn + slot->npages - 1,
flush_on_yield, false);
true, flush_on_yield, false);
}
static __always_inline bool walk_slot_rmaps_4k(struct kvm *kvm,
@@ -6600,7 +6604,7 @@ static bool kvm_rmap_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_e
flush = __walk_slot_rmaps(kvm, memslot, __kvm_zap_rmap,
PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL,
start, end - 1, true, flush);
start, end - 1, true, true, flush);
}
}
@@ -6888,7 +6892,7 @@ static void kvm_shadow_mmu_try_split_huge_pages(struct kvm *kvm,
*/
for (level = KVM_MAX_HUGEPAGE_LEVEL; level > target_level; level--)
__walk_slot_rmaps(kvm, slot, shadow_mmu_try_split_huge_pages,
level, level, start, end - 1, true, false);
level, level, start, end - 1, true, true, false);
}
/* Must be called with the mmu_lock held in write-mode. */