Messages in this thread | | | Date | Tue, 27 Nov 2012 21:32:46 -0200 | From | Marcelo Tosatti <> | Subject | Re: [PATCH 2/3] KVM: x86: let reexecute_instruction work for tdp |
| |
On Tue, Nov 27, 2012 at 11:13:11AM +0800, Xiao Guangrong wrote: > >> +static bool reexecute_instruction(struct kvm_vcpu *vcpu, unsigned long cr2) > >> { > >> - gpa_t gpa; > >> + gpa_t gpa = cr2; > >> pfn_t pfn; > >> > >> - if (tdp_enabled) > >> + if (!ACCESS_ONCE(vcpu->kvm->arch.indirect_shadow_pages)) > >> return false; > > > > How is indirect_shadow_pages protected? Why is ACCESS_ONCE() being used > > to read it? > > Hi Marcelo, > > It is protected by mmu-lock for it only be changed when mmu-lock is hold. And > ACCESS_ONCE is used on read path avoiding magic optimization from compiler.
Please switch to mmu_lock protection, there is no reason to have access to this variable locklessly - not performance critical.
For example, there is no use of barriers when modifying the variable.
| |