Messages in this thread | | | Subject | Re: [PATCH RFC 2/6] KVM: x86: extend struct kvm_vcpu_pv_apf_data with token info | From | Gavin Shan <> | Date | Tue, 5 May 2020 09:52:45 +1000 |
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Hi Vitaly,
On 4/29/20 7:36 PM, Vitaly Kuznetsov wrote: > Currently, APF mechanism relies on the #PF abuse where the token is being > passed through CR2. If we switch to using interrupts to deliver page-ready > notifications we need a different way to pass the data. Extent the existing > 'struct kvm_vcpu_pv_apf_data' with token information. > > Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com> > --- > arch/x86/include/uapi/asm/kvm_para.h | 3 ++- > arch/x86/kvm/x86.c | 10 ++++++---- > 2 files changed, 8 insertions(+), 5 deletions(-) > > diff --git a/arch/x86/include/uapi/asm/kvm_para.h b/arch/x86/include/uapi/asm/kvm_para.h > index 2a8e0b6b9805..df2ba34037a2 100644 > --- a/arch/x86/include/uapi/asm/kvm_para.h > +++ b/arch/x86/include/uapi/asm/kvm_para.h > @@ -113,7 +113,8 @@ struct kvm_mmu_op_release_pt { > > struct kvm_vcpu_pv_apf_data { > __u32 reason; > - __u8 pad[60]; > + __u32 token; > + __u8 pad[56]; > __u32 enabled; > }; > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index b93133ee07ba..7c21c0cf0a33 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -2662,7 +2662,7 @@ static int kvm_pv_enable_async_pf(struct kvm_vcpu *vcpu, u64 data) > } > > if (kvm_gfn_to_hva_cache_init(vcpu->kvm, &vcpu->arch.apf.data, gpa, > - sizeof(u32))) > + sizeof(u64))) > return 1; > > vcpu->arch.apf.send_user_only = !(data & KVM_ASYNC_PF_SEND_ALWAYS); > @@ -10352,8 +10352,9 @@ static void kvm_del_async_pf_gfn(struct kvm_vcpu *vcpu, gfn_t gfn) > } > } > > -static int apf_put_user(struct kvm_vcpu *vcpu, u32 val) > +static int apf_put_user(struct kvm_vcpu *vcpu, u32 reason, u32 token) > { > + u64 val = (u64)token << 32 | reason; > > return kvm_write_guest_cached(vcpu->kvm, &vcpu->arch.apf.data, &val, > sizeof(val)); > @@ -10405,7 +10406,8 @@ void kvm_arch_async_page_not_present(struct kvm_vcpu *vcpu, > kvm_add_async_pf_gfn(vcpu, work->arch.gfn); > > if (kvm_can_deliver_async_pf(vcpu) && > - !apf_put_user(vcpu, KVM_PV_REASON_PAGE_NOT_PRESENT)) { > + !apf_put_user(vcpu, KVM_PV_REASON_PAGE_NOT_PRESENT, > + work->arch.token)) { > fault.vector = PF_VECTOR; > fault.error_code_valid = true; > fault.error_code = 0; > @@ -10438,7 +10440,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu, > trace_kvm_async_pf_ready(work->arch.token, work->cr2_or_gpa); > > if (vcpu->arch.apf.msr_val & KVM_ASYNC_PF_ENABLED && > - !apf_put_user(vcpu, KVM_PV_REASON_PAGE_READY)) { > + !apf_put_user(vcpu, KVM_PV_REASON_PAGE_READY, work->arch.token)) { > fault.vector = PF_VECTOR; > fault.error_code_valid = true; > fault.error_code = 0; >
It would be as below based on two facts: (1) token is more important than reason; (2) token will be put into high word of @val. I think apf_{get,put}_user() might be worthy to be inline. However, it's not a big deal.
static inline int apf_put_user(struct kvm_vcpu *vcpu, u32 token, u32 reason)
Thanks, Gavin
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