Hi Paolo,
于 9/24/14, 3:04 PM, Paolo Bonzini 写道:
Il 24/09/2014 04:27, Wanpeng Li ha scritto:
Hi Andres,
On Mon, Sep 22, 2014 at 02:54:42PM -0700, Andres Lagar-Cavilla wrote:
1. We were calling clear_flush_young_notify in unmap_one, but we are
within an mmu notifier invalidate range scope. The spte exists no more
(due to range_start) and the accessed bit info has already been
propagated (due to kvm_pfn_set_accessed). Simply call
clear_flush_young.
2. We clear_flush_young on a primary MMU PMD, but this may be mapped
as a collection of PTEs by the secondary MMU (e.g. during log-dirty).
This required expanding the interface of the clear_flush_young mmu
notifier, so a lot of code has been trivially touched.
3. In the absence of shadow_accessed_mask (e.g. EPT A bit), we emulate
the access bit by blowing the spte. This requires proper synchronizing
with MMU notifier consumers, like every other removal of spte's does.
[...]
---
+ BUG_ON(!shadow_accessed_mask);
for (sptep = rmap_get_first(*rmapp, &iter); sptep;
sptep = rmap_get_next(&iter)) {
+ struct kvm_mmu_page *sp;
+ gfn_t gfn;
BUG_ON(!is_shadow_present_pte(*sptep));
+ /* From spte to gfn. */
+ sp = page_header(__pa(sptep));
+ gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
if (*sptep & shadow_accessed_mask) {
young = 1;
clear_bit((ffs(shadow_accessed_mask) - 1),
(unsigned long *)sptep);
}
+ trace_kvm_age_page(gfn, slot, young);
IIUC, all the rmapps in this for loop are against the same gfn which
results in the above trace point dump the message duplicated.
You're right; Andres's patch "[PATCH] kvm/x86/mmu: Pass gfn and level to
rmapp callback" helps avoiding that.
From Andres's patch "[PATCH] kvm/x86/mmu: Pass gfn and level to rmapp
callback"
@@ -1410,25 +1421,20 @@ static int kvm_age_rmapp(struct kvm *kvm,
unsigned long *rmapp,
for (sptep = rmap_get_first(*rmapp, &iter); sptep;
sptep = rmap_get_next(&iter)) {
- struct kvm_mmu_page *sp;
- gfn_t gfn;
BUG_ON(!is_shadow_present_pte(*sptep));
- /* From spte to gfn. */
- sp = page_header(__pa(sptep));
- gfn = kvm_mmu_page_get_gfn(sp, sptep - sp->spt);
-
if (*sptep & shadow_accessed_mask) {
young = 1;
clear_bit((ffs(shadow_accessed_mask) - 1),
(unsigned long *)sptep);
}
- trace_kvm_age_page(gfn, slot, young);
+ trace_kvm_age_page(gfn, level, slot, young);
}
return young;
}
This trace point still dup duplicated message for the same gfn in the
for loop.
Regards,
Wanpeng Li
Paolo
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