mirrors/linux
2
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git synced 2026-05-07 23:20:32 -04:00
Code Issues Packages Projects Releases Wiki Activity

KVM: x86/mmu: Stop processing TDP MMU roots for test_age if young SPTE found

Browse Source 
Return immediately if a young SPTE is found when testing, but not updating,
SPTEs.  The return value is a boolean, i.e. whether there is one young SPTE
or fifty is irrelevant (ignoring the fact that it's impossible for there to
be fifty SPTEs, as KVM has a hard limit on the number of valid TDP MMU
roots).

Link: https://lore.kernel.org/r/20241011021051.1557902-15-seanjc@google.com
[sean: use guard(rcu)(), as suggested by Paolo]
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson
2024-10-10 19:10:46 -07:00
parent 526e609f05
commit 51192ebdd1
1 changed files with 35 additions and 44 deletions
Download Patch File Download Diff File Expand all files Collapse all files

79
arch/x86/kvm/mmu/tdp_mmu.c
View File

@@ -1192,35 +1192,6 @@ bool kvm_tdp_mmu_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range,
return flush;
}
typedef bool (*tdp_handler_t)(struct kvm *kvm, struct tdp_iter *iter,
struct kvm_gfn_range *range);
static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm,
struct kvm_gfn_range *range,
tdp_handler_t handler)
{
struct kvm_mmu_page *root;
struct tdp_iter iter;
bool ret = false;
/*
* Don't support rescheduling, none of the MMU notifiers that funnel
* into this helper allow blocking; it'd be dead, wasteful code. Note,
* this helper must NOT be used to unmap GFNs, as it processes only
* valid roots!
*/
for_each_valid_tdp_mmu_root(kvm, root, range->slot->as_id) {
rcu_read_lock();
tdp_root_for_each_leaf_pte(iter, root, range->start, range->end)
ret |= handler(kvm, &iter, range);
rcu_read_unlock();
}
return ret;
}
/*
* Mark the SPTEs range of GFNs [start, end) unaccessed and return non-zero
* if any of the GFNs in the range have been accessed.
@@ -1229,15 +1200,10 @@ static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm,
* from the clear_young() or clear_flush_young() notifier, which uses the
* return value to determine if the page has been accessed.
*/
static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter,
struct kvm_gfn_range *range)
static void kvm_tdp_mmu_age_spte(struct tdp_iter *iter)
{
u64 new_spte;
/* If we have a non-accessed entry we don't need to change the pte. */
if (!is_accessed_spte(iter->old_spte))
return false;
if (spte_ad_enabled(iter->old_spte)) {
iter->old_spte = tdp_mmu_clear_spte_bits(iter->sptep,
iter->old_spte,
@@ -1253,23 +1219,48 @@ static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter,
trace_kvm_tdp_mmu_spte_changed(iter->as_id, iter->gfn, iter->level,
iter->old_spte, new_spte);
return true;
}
static bool __kvm_tdp_mmu_age_gfn_range(struct kvm *kvm,
struct kvm_gfn_range *range,
bool test_only)
{
struct kvm_mmu_page *root;
struct tdp_iter iter;
bool ret = false;
/*
* Don't support rescheduling, none of the MMU notifiers that funnel
* into this helper allow blocking; it'd be dead, wasteful code. Note,
* this helper must NOT be used to unmap GFNs, as it processes only
* valid roots!
*/
for_each_valid_tdp_mmu_root(kvm, root, range->slot->as_id) {
guard(rcu)();
tdp_root_for_each_leaf_pte(iter, root, range->start, range->end) {
if (!is_accessed_spte(iter.old_spte))
continue;
if (test_only)
return true;
ret = true;
kvm_tdp_mmu_age_spte(&iter);
}
}
return ret;
}
bool kvm_tdp_mmu_age_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range)
{
return kvm_tdp_mmu_handle_gfn(kvm, range, age_gfn_range);
}
static bool test_age_gfn(struct kvm *kvm, struct tdp_iter *iter,
struct kvm_gfn_range *range)
{
return is_accessed_spte(iter->old_spte);
return __kvm_tdp_mmu_age_gfn_range(kvm, range, false);
}
bool kvm_tdp_mmu_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
{
return kvm_tdp_mmu_handle_gfn(kvm, range, test_age_gfn);
return __kvm_tdp_mmu_age_gfn_range(kvm, range, true);
}
/*