shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-08 11:50:43 +09:00
Code Issues Packages Projects Releases Wiki Activity

KVM: x86/mmu: Clear only A-bit (if enabled) when aging TDP MMU SPTEs

Browse Source 
Use tdp_mmu_clear_spte_bits() when clearing the Accessed bit in TDP MMU
SPTEs so as to use an atomic-AND instead of XCHG to clear the A-bit.
Similar to the D-bit story, this will allow KVM to bypass
__handle_changed_spte() by ensuring only the A-bit is modified.

Link: https://lore.kernel.org/all/Y9HcHRBShQgjxsQb@google.com
Signed-off-by: Vipin Sharma <vipinsh@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
[sean: massage changelog]
Link: https://lore.kernel.org/r/20230321220021.2119033-9-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Vipin Sharma
2023-03-21 15:00:16 -07:00
committed by Sean Christopherson
parent e73008705d
commit 7ee131e3a3
1 changed files with 21 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

38
arch/x86/kvm/mmu/tdp_mmu.c
View File

@@ -756,13 +756,6 @@ static inline void tdp_mmu_set_spte(struct kvm *kvm, struct tdp_iter *iter,
_tdp_mmu_set_spte(kvm, iter, new_spte, true);
}
static inline void tdp_mmu_set_spte_no_acc_track(struct kvm *kvm,
struct tdp_iter *iter,
u64 new_spte)
{
_tdp_mmu_set_spte(kvm, iter, new_spte, false);
}
#define tdp_root_for_each_pte(_iter, _root, _start, _end) \
for_each_tdp_pte(_iter, _root, _start, _end)
@@ -1248,33 +1241,44 @@ static __always_inline bool kvm_tdp_mmu_handle_gfn(struct kvm *kvm,
/*
* Mark the SPTEs range of GFNs [start, end) unaccessed and return non-zero
* if any of the GFNs in the range have been accessed.
*
* No need to mark the corresponding PFN as accessed as this call is coming
* 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)
{
u64 new_spte = 0;
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;
new_spte = iter->old_spte;
if (spte_ad_enabled(new_spte)) {
new_spte &= ~shadow_accessed_mask;
if (spte_ad_enabled(iter->old_spte)) {
iter->old_spte = tdp_mmu_clear_spte_bits(iter->sptep,
iter->old_spte,
shadow_accessed_mask,
iter->level);
new_spte = iter->old_spte & ~shadow_accessed_mask;
} else {
/*
* Capture the dirty status of the page, so that it doesn't get
* lost when the SPTE is marked for access tracking.
*/
if (is_writable_pte(new_spte))
kvm_set_pfn_dirty(spte_to_pfn(new_spte));
if (is_writable_pte(iter->old_spte))
kvm_set_pfn_dirty(spte_to_pfn(iter->old_spte));
new_spte = mark_spte_for_access_track(new_spte);
new_spte = mark_spte_for_access_track(iter->old_spte);
iter->old_spte = kvm_tdp_mmu_write_spte(iter->sptep,
iter->old_spte, new_spte,
iter->level);
}
tdp_mmu_set_spte_no_acc_track(kvm, iter, new_spte);
__handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte,
new_spte, iter->level, false);
handle_changed_spte_dirty_log(kvm, iter->as_id, iter->gfn,
iter->old_spte, new_spte, iter->level);
return true;
}