On Mon, Mar 20, 2017 at 06:26:42PM +0000, Suzuki K Poulose wrote: > In order to perform an operation on a gpa range, the hyp iterates
the hyp ? > over each page in a user memory slot for the given range. This is > inefficient while dealing with a big range (e.g, a VMA), especially > while unmaping a range. At present, with stage2 unmap on a range with > a hugepage backed region, we clear the PMD when we unmap the first > page in the loop. The remaining iterations simply traverse the page table > down to the PMD level only to see that nothing is in there. > > This patch reworks the code to invoke the callback handlers on the > biggest range possible within the memory slot to avoid reduce the > number of iterations. avoid reduce? did you mean "to reduce the number of times the handler is called" ? > > Cc: Marc Zyngier <[email protected]> > Cc: Christoffer Dall <[email protected]> > Signed-off-by: Suzuki K Poulose <[email protected]> > --- > arch/arm/kvm/mmu.c | 31 +++++++++++++------------------ > 1 file changed, 13 insertions(+), 18 deletions(-) > > diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c > index 37e67f5..8357fed 100644 > --- a/arch/arm/kvm/mmu.c > +++ b/arch/arm/kvm/mmu.c > @@ -1524,7 +1524,8 @@ static int handle_hva_to_gpa(struct kvm *kvm, > unsigned long start, > unsigned long end, > int (*handler)(struct kvm *kvm, > - gpa_t gpa, void *data), > + gpa_t gpa, u64 size, > + void *data), > void *data) > { > struct kvm_memslots *slots; > @@ -1536,7 +1537,7 @@ static int handle_hva_to_gpa(struct kvm *kvm, > /* we only care about the pages that the guest sees */ > kvm_for_each_memslot(memslot, slots) { > unsigned long hva_start, hva_end; > - gfn_t gfn, gfn_end; > + gfn_t gpa; > > hva_start = max(start, memslot->userspace_addr); > hva_end = min(end, memslot->userspace_addr + > @@ -1544,25 +1545,16 @@ static int handle_hva_to_gpa(struct kvm *kvm, > if (hva_start >= hva_end) > continue; > > - /* > - * {gfn(page) | page intersects with [hva_start, hva_end)} = > - * {gfn_start, gfn_start+1, ..., gfn_end-1}. > - */ > - gfn = hva_to_gfn_memslot(hva_start, memslot); > - gfn_end = hva_to_gfn_memslot(hva_end + PAGE_SIZE - 1, memslot); > - > - for (; gfn < gfn_end; ++gfn) { > - gpa_t gpa = gfn << PAGE_SHIFT; > - ret |= handler(kvm, gpa, data); > - } > + gpa = hva_to_gfn_memslot(hva_start, memslot) << PAGE_SHIFT; > + ret |= handler(kvm, gpa, (u64)(hva_end - hva_start), data); > } > > return ret; > } > > -static int kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, void *data) > +static int kvm_unmap_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void > *data) > { > - unmap_stage2_range(kvm, gpa, PAGE_SIZE); > + unmap_stage2_range(kvm, gpa, size); > return 0; > } > > @@ -1589,10 +1581,11 @@ int kvm_unmap_hva_range(struct kvm *kvm, > return 0; > } > > -static int kvm_set_spte_handler(struct kvm *kvm, gpa_t gpa, void *data) > +static int kvm_set_spte_handler(struct kvm *kvm, gpa_t gpa, u64 size, void > *data) > { > pte_t *pte = (pte_t *)data; > > + WARN_ON(size != PAGE_SIZE); > /* > * We can always call stage2_set_pte with KVM_S2PTE_FLAG_LOGGING_ACTIVE > * flag clear because MMU notifiers will have unmapped a huge PMD before > @@ -1618,11 +1611,12 @@ void kvm_set_spte_hva(struct kvm *kvm, unsigned long > hva, pte_t pte) > handle_hva_to_gpa(kvm, hva, end, &kvm_set_spte_handler, &stage2_pte); > } > > -static int kvm_age_hva_handler(struct kvm *kvm, gpa_t gpa, void *data) > +static int kvm_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, void > *data) > { > pmd_t *pmd; > pte_t *pte; > > + WARN_ON(size != PAGE_SIZE && size != PMD_SIZE); > pmd = stage2_get_pmd(kvm, NULL, gpa); > if (!pmd || pmd_none(*pmd)) /* Nothing there */ > return 0; > @@ -1637,11 +1631,12 @@ static int kvm_age_hva_handler(struct kvm *kvm, gpa_t > gpa, void *data) > return stage2_ptep_test_and_clear_young(pte); > } > > -static int kvm_test_age_hva_handler(struct kvm *kvm, gpa_t gpa, void *data) > +static int kvm_test_age_hva_handler(struct kvm *kvm, gpa_t gpa, u64 size, > void *data) > { > pmd_t *pmd; > pte_t *pte; > > + WARN_ON(size != PAGE_SIZE && size != PMD_SIZE); > pmd = stage2_get_pmd(kvm, NULL, gpa); > if (!pmd || pmd_none(*pmd)) /* Nothing there */ > return 0; > -- > 2.7.4 > Otherwise looks good: I can fix up the commit message when applying this. Reviewed-by: Christoffer Dall <[email protected]> _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
