lkml.org 
[lkml]   [2013]   [Nov]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 01/15] KVM: MMU: properly check last spte in fast_page_fault()
    On Wed, Oct 23, 2013 at 09:29:19PM +0800, Xiao Guangrong wrote:
    > Using sp->role.level instead of @level since @level is not got from the
    > page table hierarchy
    >
    > There is no issue in current code since the fast page fault currently only
    > fixes the fault caused by dirty-log that is always on the last level
    > (level = 1)
    >
    > This patch makes the code more readable and avoids potential issue in the
    > further development
    >
    > Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
    > ---
    > arch/x86/kvm/mmu.c | 10 ++++++----
    > 1 file changed, 6 insertions(+), 4 deletions(-)
    >
    > diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
    > index 40772ef..d2aacc2 100644
    > --- a/arch/x86/kvm/mmu.c
    > +++ b/arch/x86/kvm/mmu.c
    > @@ -2798,9 +2798,9 @@ static bool page_fault_can_be_fast(u32 error_code)
    > }
    >
    > static bool
    > -fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, u64 *sptep, u64 spte)
    > +fast_pf_fix_direct_spte(struct kvm_vcpu *vcpu, struct kvm_mmu_page *sp,
    > + u64 *sptep, u64 spte)
    > {
    > - struct kvm_mmu_page *sp = page_header(__pa(sptep));
    > gfn_t gfn;
    >
    > WARN_ON(!sp->role.direct);
    > @@ -2826,6 +2826,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
    > u32 error_code)
    > {
    > struct kvm_shadow_walk_iterator iterator;
    > + struct kvm_mmu_page *sp;
    > bool ret = false;
    > u64 spte = 0ull;
    >
    > @@ -2846,7 +2847,8 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
    > goto exit;
    > }
    >
    > - if (!is_last_spte(spte, level))
    > + sp = page_header(__pa(iterator.sptep));
    > + if (!is_last_spte(spte, sp->role.level))
    > goto exit;
    >
    > /*
    > @@ -2872,7 +2874,7 @@ static bool fast_page_fault(struct kvm_vcpu *vcpu, gva_t gva, int level,
    > * the gfn is not stable for indirect shadow page.
    > * See Documentation/virtual/kvm/locking.txt to get more detail.
    > */
    > - ret = fast_pf_fix_direct_spte(vcpu, iterator.sptep, spte);
    > + ret = fast_pf_fix_direct_spte(vcpu, sp, iterator.sptep, spte);
    > exit:
    > trace_fast_page_fault(vcpu, gva, error_code, iterator.sptep,
    > spte, ret);
    > --
    > 1.8.1.4


    Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>



    \
     
     \ /
      Last update: 2013-11-12 01:41    [W:5.087 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site