> -----Original Message-----
> From: Paolo Bonzini [mailto:[email protected]] On Behalf Of Paolo
> Bonzini
> Sent: Monday, October 07, 2013 5:35 PM
> To: Alexander Graf
> Cc: Bhushan Bharat-R65777; Paul Mackerras; Wood Scott-B07421; kvm-
> [email protected]; [email protected] mailing list; Bhushan
> Bharat-R65777;
> Gleb Natapov
> Subject: Re: [PATCH 2/2] kvm: ppc: booke: check range page invalidation
> progress
> on page setup
>
> Il 04/10/2013 15:38, Alexander Graf ha scritto:
> >
> > On 07.08.2013, at 12:03, Bharat Bhushan wrote:
> >
> >> When the MM code is invalidating a range of pages, it calls the KVM
> >> kvm_mmu_notifier_invalidate_range_start() notifier function, which calls
> >> kvm_unmap_hva_range(), which arranges to flush all the TLBs for guest
> >> pages.
> >> However, the Linux PTEs for the range being flushed are still valid at
> >> that point. We are not supposed to establish any new references to pages
> >> in the range until the ...range_end() notifier gets called.
> >> The PPC-specific KVM code doesn't get any explicit notification of that;
> >> instead, we are supposed to use mmu_notifier_retry() to test whether we
> >> are or have been inside a range flush notifier pair while we have been
> >> referencing a page.
> >>
> >> This patch calls the mmu_notifier_retry() while mapping the guest
> >> page to ensure we are not referencing a page when in range invalidation.
> >>
> >> This call is inside a region locked with kvm->mmu_lock, which is the
> >> same lock that is called by the KVM MMU notifier functions, thus
> >> ensuring that no new notification can proceed while we are in the
> >> locked region.
> >>
> >> Signed-off-by: Bharat Bhushan <[email protected]>
> >
> > Acked-by: Alexander Graf <[email protected]>
> >
> > Gleb, Paolo, please queue for 3.12 directly.
>
> Here is the backport. The second hunk has a nontrivial conflict, so
> someone please give their {Tested,Reviewed,Compiled}-by.
{Compiled,Reviewed}-by: Bharat Bhushan <[email protected]>
Thanks
-Bharat
>
> Paolo
>
> diff --git a/arch/powerpc/kvm/e500_mmu_host.c
> b/arch/powerpc/kvm/e500_mmu_host.c
> index 1c6a9d7..c65593a 100644
> --- a/arch/powerpc/kvm/e500_mmu_host.c
> +++ b/arch/powerpc/kvm/e500_mmu_host.c
> @@ -332,6 +332,13 @@ static inline int kvmppc_e500_shadow_map(struct
> kvmppc_vcpu_e500 *vcpu_e500,
> unsigned long hva;
> int pfnmap = 0;
> int tsize = BOOK3E_PAGESZ_4K;
> + int ret = 0;
> + unsigned long mmu_seq;
> + struct kvm *kvm = vcpu_e500->vcpu.kvm;
> +
> + /* used to check for invalidations in progress */
> + mmu_seq = kvm->mmu_notifier_seq;
> + smp_rmb();
>
> /*
> * Translate guest physical to true physical, acquiring
> @@ -449,6 +456,12 @@ static inline int kvmppc_e500_shadow_map(struct
> kvmppc_vcpu_e500 *vcpu_e500,
> gvaddr &= ~((tsize_pages << PAGE_SHIFT) - 1);
> }
>
> + spin_lock(&kvm->mmu_lock);
> + if (mmu_notifier_retry(kvm, mmu_seq)) {
> + ret = -EAGAIN;
> + goto out;
> + }
> +
> kvmppc_e500_ref_setup(ref, gtlbe, pfn);
>
> kvmppc_e500_setup_stlbe(&vcpu_e500->vcpu, gtlbe, tsize,
> @@ -457,10 +470,13 @@ static inline int kvmppc_e500_shadow_map(struct
> kvmppc_vcpu_e500 *vcpu_e500,
> /* Clear i-cache for new pages */
> kvmppc_mmu_flush_icache(pfn);
>
> +out:
> + spin_unlock(&kvm->mmu_lock);
> +
> /* Drop refcount on page, so that mmu notifiers can clear it */
> kvm_release_pfn_clean(pfn);
>
> - return 0;
> + return ret;
> }
>
> /* XXX only map the one-one case, for now use TLB0 */
>
>
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