On 01/24/2013 06:36 PM, Gleb Natapov wrote: > On Wed, Jan 23, 2013 at 06:06:36PM +0800, Xiao Guangrong wrote: >> Introduce it to split the code of adjusting pte_access from the large >> function of set_spte >> >> Signed-off-by: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx> >> --- >> arch/x86/kvm/mmu.c | 63 +++++++++++++++++++++++++++++++++------------------- >> 1 files changed, 40 insertions(+), 23 deletions(-) >> >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index af8bcb2..43b7e0c 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -2324,25 +2324,18 @@ static int mmu_need_write_protect(struct kvm_vcpu *vcpu, gfn_t gfn, >> return 0; >> } >> >> -static int set_spte(struct kvm_vcpu *vcpu, u64 *sptep, >> - unsigned pte_access, int level, >> - gfn_t gfn, pfn_t pfn, bool speculative, >> - bool can_unsync, bool host_writable) >> +/* >> + * Return -1 if a race condition is detected, 1 if @gfn need to be >> + * write-protected, otherwise 0 is returned. >> + */ > That's a little bit crafty. > > Isn't it better to handle race condition in set_spte() explicitly? > Something like do: > > if (host_writable && (pte_access & ACC_WRITE_MASK) && > level > PT_PAGE_TABLE_LEVEL && has_wrprotected_page(vcpu->kvm, gfn, level)) > return 0; > > before calling vcpu_adjust_access() in set_spte()? > > Or even do: > > if ((pte_access & ACC_WRITE_MASK) && level > PT_PAGE_TABLE_LEVEL && > has_wrprotected_page(vcpu->kvm, gfn, level)) > return 0; > > After calling vcpu_adjust_access(). > > The later will create read only large page mapping where now it is not > created, but it shouldn't be a problem as far as I see. Yes. I like the later way. Will update it. Thanks for your suggestion, Gleb! -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
