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kvm: x86: mmu: Introduce a no-tracking version of mmu_spte_update

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mmu_spte_update() tracks changes in the accessed/dirty state of
the SPTE being updated and calls kvm_set_pfn_accessed/dirty
appropriately. However, in some cases (e.g. when aging the SPTE),
this shouldn't be done. mmu_spte_update_no_track() is introduced
for use in such cases.

Signed-off-by: Junaid Shahid <junaids@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Junaid Shahid 2016-12-06 16:46:14 -08:00 committed by Radim Krčmář
parent 83ef6c8155
commit f39a058d0e
1 changed files with 28 additions and 14 deletions
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42
arch/x86/kvm/mmu.c
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@ -528,6 +528,31 @@ static void mmu_spte_set(u64 *sptep, u64 new_spte)
__set_spte(sptep, new_spte);
}
/*
* Update the SPTE (excluding the PFN), but do not track changes in its
* accessed/dirty status.
*/
static u64 mmu_spte_update_no_track(u64 *sptep, u64 new_spte)
{
u64 old_spte = *sptep;
WARN_ON(!is_shadow_present_pte(new_spte));
if (!is_shadow_present_pte(old_spte)) {
mmu_spte_set(sptep, new_spte);
return old_spte;
}
if (!spte_has_volatile_bits(old_spte))
__update_clear_spte_fast(sptep, new_spte);
else
old_spte = __update_clear_spte_slow(sptep, new_spte);
WARN_ON(spte_to_pfn(old_spte) != spte_to_pfn(new_spte));
return old_spte;
}
/* Rules for using mmu_spte_update:
* Update the state bits, it means the mapped pfn is not changed.
*
@ -541,22 +566,11 @@ static void mmu_spte_set(u64 *sptep, u64 new_spte)
*/
static bool mmu_spte_update(u64 *sptep, u64 new_spte)
{
u64 old_spte = *sptep;
bool flush = false;
u64 old_spte = mmu_spte_update_no_track(sptep, new_spte);
WARN_ON(!is_shadow_present_pte(new_spte));
if (!is_shadow_present_pte(old_spte)) {
mmu_spte_set(sptep, new_spte);
return flush;
}
if (!spte_has_volatile_bits(old_spte))
__update_clear_spte_fast(sptep, new_spte);
else
old_spte = __update_clear_spte_slow(sptep, new_spte);
WARN_ON(spte_to_pfn(old_spte) != spte_to_pfn(new_spte));
if (!is_shadow_present_pte(old_spte))
return false;
/*
* For the spte updated out of mmu-lock is safe, since