Re: [PATCH v2 5/5] KVM: MMU: introduce FNAME(prefetch_gpte)

From: Xiao Guangrong
Date: Fri Sep 14 2012 - 06:13:21 EST


On 09/14/2012 05:59 PM, Xiao Guangrong wrote:

> + return FNAME(prefetch_gpte)(vcpu, sp, spte, gptep[i], true);

Sorry, this was wrong. Update this patch.

[PATCH v2 5/5] KVM: MMU: introduce FNAME(prefetch_gpte)

The only different thing between FNAME(update_pte) and FNAME(pte_prefetch)
is that the former is allowed to prefetch gfn from dirty logged slot, so
introduce a common function to prefetch spte

Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/paging_tmpl.h | 50 ++++++++++++++++---------------------------
1 files changed, 19 insertions(+), 31 deletions(-)

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index 1a738c5..32facf7 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -356,35 +356,45 @@ no_present:
return true;
}

-static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
- u64 *spte, const void *pte)
+static void
+FNAME(prefetch_gpte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
+ u64 *spte, pt_element_t gpte, bool no_dirty_log)
{
- pt_element_t gpte;
unsigned pte_access;
+ gfn_t gfn;
pfn_t pfn;

- gpte = *(const pt_element_t *)pte;
if (FNAME(prefetch_invalid_gpte)(vcpu, sp, spte, gpte))
return;

pgprintk("%s: gpte %llx spte %p\n", __func__, (u64)gpte, spte);
+
+ gfn = gpte_to_gfn(gpte);
pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte, true);
- pfn = gfn_to_pfn_atomic(vcpu->kvm, gpte_to_gfn(gpte));
+ pfn = pte_prefetch_gfn_to_pfn(vcpu, gfn,
+ no_dirty_log && (pte_access & ACC_WRITE_MASK));
if (mmu_invalid_pfn(pfn))
return;

/*
* we call mmu_set_spte() with host_writable = true because that
- * vcpu->arch.update_pte.pfn was fetched from get_user_pages(write = 1).
+ * pte_prefetch_gfn_to_pfn always gets a writable pfn.
*/
mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0,
- NULL, PT_PAGE_TABLE_LEVEL,
- gpte_to_gfn(gpte), pfn, true, true);
+ NULL, PT_PAGE_TABLE_LEVEL, gfn, pfn, true, true);

if (!is_error_pfn(pfn))
kvm_release_pfn_clean(pfn);
}

+static void FNAME(update_pte)(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
+ u64 *spte, const void *pte)
+{
+ pt_element_t gpte = *(const pt_element_t *)pte;
+
+ return FNAME(prefetch_gpte)(vcpu, sp, spte, gpte, false);
+}
+
static bool FNAME(gpte_changed)(struct kvm_vcpu *vcpu,
struct guest_walker *gw, int level)
{
@@ -428,35 +438,13 @@ static void FNAME(pte_prefetch)(struct kvm_vcpu *vcpu, struct guest_walker *gw,
spte = sp->spt + i;

for (i = 0; i < PTE_PREFETCH_NUM; i++, spte++) {
- pt_element_t gpte;
- unsigned pte_access;
- gfn_t gfn;
- pfn_t pfn;
-
if (spte == sptep)
continue;

if (is_shadow_present_pte(*spte))
continue;

- gpte = gptep[i];
-
- if (FNAME(prefetch_invalid_gpte)(vcpu, sp, spte, gpte))
- continue;
-
- pte_access = sp->role.access & FNAME(gpte_access)(vcpu, gpte,
- true);
- gfn = gpte_to_gfn(gpte);
- pfn = pte_prefetch_gfn_to_pfn(vcpu, gfn,
- pte_access & ACC_WRITE_MASK);
- if (mmu_invalid_pfn(pfn))
- break;
-
- mmu_set_spte(vcpu, spte, sp->role.access, pte_access, 0, 0,
- NULL, PT_PAGE_TABLE_LEVEL, gfn,
- pfn, true, true);
- if (!is_error_pfn(pfn))
- kvm_release_pfn_clean(pfn);
+ FNAME(prefetch_gpte)(vcpu, sp, spte, gptep[i], true);
}
}

--
1.7.7.6

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