| Message ID | 20200429093634.1514902-3-vkuznets@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: x86: Interrupt-based mechanism for async_pf 'page present' notifications | expand |
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
Gavin Shan <gshan@redhat.com> writes: > 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. This is to be changed in v1 as we agreed to drop page-ready delivery via #PF completely. > static inline int apf_put_user(struct kvm_vcpu *vcpu, u32 token, u32 reason) > Yes, it makes sense to inline these. Thanks!
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;
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(-)