lkml.org 
[lkml]   [2018]   [Jul]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] KVM/MMU: Combine flushing remote tlb in mmu_set_spte()
From
Date
On 07/24/2018 07:35 AM, Paolo Bonzini wrote:
> On 24/07/2018 10:17, Tianyu Lan wrote:
>> mmu_set_spte() flushes remote tlbs for drop_parent_pte/drop_spte()
>> and set_spte() separately. This may introduce redundant flush. This
>> patch is to combine these flushes and check flush request after
>> calling set_spte().
>>
>> Signed-off-by: Lan Tianyu <Tianyu.Lan@microsoft.com>
>
> Looks good, but I'd like a second opinion. Guangrong, Junaid, can you
> review this?
>
> Thanks,
>
> Paolo
>
>> ---
>> arch/x86/kvm/mmu.c | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
>> index 22a7984..8f21632 100644
>> --- a/arch/x86/kvm/mmu.c
>> +++ b/arch/x86/kvm/mmu.c
>> @@ -2901,6 +2901,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
>> int rmap_count;
>> int set_spte_ret;
>> int ret = RET_PF_RETRY;
>> + bool flush = false;
>>
>> pgprintk("%s: spte %llx write_fault %d gfn %llx\n", __func__,
>> *sptep, write_fault, gfn);
>> @@ -2917,12 +2918,12 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
>>
>> child = page_header(pte & PT64_BASE_ADDR_MASK);
>> drop_parent_pte(child, sptep);
>> - kvm_flush_remote_tlbs(vcpu->kvm);
>> + flush = true;
>> } else if (pfn != spte_to_pfn(*sptep)) {
>> pgprintk("hfn old %llx new %llx\n",
>> spte_to_pfn(*sptep), pfn);
>> drop_spte(vcpu->kvm, sptep);
>> - kvm_flush_remote_tlbs(vcpu->kvm);
>> + flush = true;
>> } else
>> was_rmapped = 1;
>> }
>> @@ -2934,7 +2935,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep, unsigned pte_access,
>> ret = RET_PF_EMULATE;
>> kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
>> }
>> - if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH)
>> + if (set_spte_ret & SET_SPTE_NEED_REMOTE_TLB_FLUSH || flush)
>> kvm_flush_remote_tlbs(vcpu->kvm);
>>
>> if (unlikely(is_mmio_spte(*sptep)))
>>
>

Reviewed-by: Junaid Shahid <junaids@google.com>

\
 
 \ /
  Last update: 2018-07-25 04:27    [W:0.045 / U:1.212 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site