On Wed, Dec 16, 2020 at 08:28:44PM +0800, Yanan Wang wrote: > We now mark the page dirty and set the bitmap before calling fault handlers > in user_mem_abort(), and we might end up having spurious dirty pages if > update of permissions or mapping has failed. > So, mark the page dirty only if the fault is handled successfully. > > Let the guest directly enter again but not return to userspace if we were > trying to recreate the same mapping or only change access permissions > with BBM, which is not permitted in the mapping path. > > Signed-off-by: Yanan Wang <[email protected]> > --- > arch/arm64/kvm/mmu.c | 18 ++++++++++++++---- > 1 file changed, 14 insertions(+), 4 deletions(-) > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > index 75814a02d189..72e516a10914 100644 > --- a/arch/arm64/kvm/mmu.c > +++ b/arch/arm64/kvm/mmu.c > @@ -879,11 +879,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, > phys_addr_t fault_ipa, > if (vma_pagesize == PAGE_SIZE && !force_pte) > vma_pagesize = transparent_hugepage_adjust(memslot, hva, > &pfn, &fault_ipa); > - if (writable) { > + if (writable) > prot |= KVM_PGTABLE_PROT_W; > - kvm_set_pfn_dirty(pfn); > - mark_page_dirty(kvm, gfn); > - } > > if (fault_status != FSC_PERM && !device) > clean_dcache_guest_page(pfn, vma_pagesize); > @@ -911,6 +908,19 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, > phys_addr_t fault_ipa, > memcache); > } > > + /* Mark the page dirty only if the fault is handled successfully */ > + if (writable && !ret) { > + kvm_set_pfn_dirty(pfn); > + mark_page_dirty(kvm, gfn); > + } > + > + /* Let the guest directly enter again if we were trying to recreate the > + * same mapping or only change access permissions with BBM, which is not > + * permitted in the mapping path. > + */ > + if (ret == -EAGAIN) > + ret = 0;
Maybe just 'return ret != -EAGAIN ? ret : 0;' at the end of the function? Will
