From: Maxim Levitsky <mlevitsk@redhat.com>
To: Nicolas Saenz Julienne <nsaenz@amazon.com>, kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, linux-hyperv@vger.kernel.org,
pbonzini@redhat.com, seanjc@google.com, vkuznets@redhat.com,
anelkz@amazon.com, graf@amazon.com, dwmw@amazon.co.uk,
jgowans@amazon.com, corbert@lwn.net, kys@microsoft.com,
haiyangz@microsoft.com, decui@microsoft.com, x86@kernel.org,
linux-doc@vger.kernel.org
Subject: Re: [RFC 06/33] KVM: x86: hyper-v: Introduce VTL awareness to Hyper-V's PV-IPIs
Date: Tue, 05 Dec 2023 17:02:40 +0200 [thread overview]
Message-ID: <72ab3fa2932dc661a4e0e124ac630e6bb269ebd4.camel@redhat.com> (raw)
In-Reply-To: <CXD538WSGHGC.BMUQF0OJSSW4@amazon.com>
On Fri, 2023-12-01 at 16:31 +0000, Nicolas Saenz Julienne wrote:
> On Tue Nov 28, 2023 at 7:14 AM UTC, Maxim Levitsky wrote:
> > On Wed, 2023-11-08 at 11:17 +0000, Nicolas Saenz Julienne wrote:
> > > HVCALL_SEND_IPI and HVCALL_SEND_IPI_EX allow targeting specific a
> > > specific VTL. Honour the requests.
> > >
> > > Signed-off-by: Nicolas Saenz Julienne <nsaenz@amazon.com>
> > > ---
> > > arch/x86/kvm/hyperv.c | 24 +++++++++++++++++-------
> > > arch/x86/kvm/trace.h | 20 ++++++++++++--------
> > > include/asm-generic/hyperv-tlfs.h | 6 ++++--
> > > 3 files changed, 33 insertions(+), 17 deletions(-)
> > >
> > > diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> > > index d4b1b53ea63d..2cf430f6ddd8 100644
> > > --- a/arch/x86/kvm/hyperv.c
> > > +++ b/arch/x86/kvm/hyperv.c
> > > @@ -2230,7 +2230,7 @@ static u64 kvm_hv_flush_tlb(struct kvm_vcpu *vcpu, struct kvm_hv_hcall *hc)
> > > }
> > >
> > > static void kvm_hv_send_ipi_to_many(struct kvm *kvm, u32 vector,
> > > - u64 *sparse_banks, u64 valid_bank_mask)
> > > + u64 *sparse_banks, u64 valid_bank_mask, int vtl)
> > > {
> > > struct kvm_lapic_irq irq = {
> > > .delivery_mode = APIC_DM_FIXED,
> > > @@ -2245,6 +2245,9 @@ static void kvm_hv_send_ipi_to_many(struct kvm *kvm, u32 vector,
> > > valid_bank_mask, sparse_banks))
> > > continue;
> > >
> > > + if (kvm_hv_get_active_vtl(vcpu) != vtl)
> > > + continue;
> >
> > Do I understand correctly that this is a temporary limitation?
> > In other words, can a vCPU running in VTL1 send an IPI to a vCPU running VTL0,
> > forcing the target vCPU to do async switch to VTL1?
> > I think that this is possible.
>
> The diff is missing some context. See this simplified implementation
> (when all_cpus is set in the parent function):
>
> static void kvm_hv_send_ipi_to_many(struct kvm *kvm, u32 vector, int vtl)
> {
> [...]
> kvm_for_each_vcpu(i, vcpu, kvm) {
> if (kvm_hv_get_active_vtl(vcpu) != vtl)
> continue;
>
> kvm_apic_set_irq(vcpu, &irq, NULL);
> }
> }
>
> With the one vCPU per VTL approach, kvm_for_each_vcpu() will iterate
> over *all* vCPUs regardless of their VTL. The IPI is targetted at a
> specific VTL, hence the need to filter.
>
> VTL1 -> VTL0 IPIs are supported and happen (although they are extremely
> rare).
Makes sense now, thanks!
Best regards,
Maxim Levitsky
>
> Nicolas
>
next prev parent reply other threads:[~2023-12-05 15:03 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-08 11:17 [RFC 0/33] KVM: x86: hyperv: Introduce VSM support Nicolas Saenz Julienne
2023-11-08 11:17 ` [RFC 01/33] KVM: x86: Decouple lapic.h from hyperv.h Nicolas Saenz Julienne
2023-11-08 16:11 ` Sean Christopherson
2023-11-08 11:17 ` [RFC 02/33] KVM: x86: Introduce KVM_CAP_APIC_ID_GROUPS Nicolas Saenz Julienne
2023-11-08 12:11 ` Alexander Graf
2023-11-08 17:47 ` Sean Christopherson
2023-11-10 18:46 ` Nicolas Saenz Julienne
2023-11-28 6:56 ` Maxim Levitsky
2023-12-01 15:25 ` Nicolas Saenz Julienne
2023-11-08 11:17 ` [RFC 03/33] KVM: x86: hyper-v: Introduce XMM output support Nicolas Saenz Julienne
2023-11-08 11:44 ` Alexander Graf
2023-11-08 12:11 ` Vitaly Kuznetsov
2023-11-08 12:16 ` Alexander Graf
2023-11-28 6:57 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 04/33] KVM: x86: hyper-v: Move hypercall page handling into separate function Nicolas Saenz Julienne
2023-11-28 7:01 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 05/33] KVM: x86: hyper-v: Introduce VTL call/return prologues in hypercall page Nicolas Saenz Julienne
2023-11-08 11:53 ` Alexander Graf
2023-11-08 14:10 ` Nicolas Saenz Julienne
2023-11-28 7:08 ` Maxim Levitsky
2023-11-28 16:33 ` Sean Christopherson
2023-12-01 16:19 ` Nicolas Saenz Julienne
2023-12-01 16:32 ` Sean Christopherson
2023-12-01 16:50 ` Nicolas Saenz Julienne
2023-12-01 17:47 ` Sean Christopherson
2023-12-01 18:15 ` Nicolas Saenz Julienne
2023-12-05 19:21 ` Sean Christopherson
2023-12-05 20:04 ` Maxim Levitsky
2023-12-06 0:07 ` Sean Christopherson
2023-12-06 16:19 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 06/33] KVM: x86: hyper-v: Introduce VTL awareness to Hyper-V's PV-IPIs Nicolas Saenz Julienne
2023-11-28 7:14 ` Maxim Levitsky
2023-12-01 16:31 ` Nicolas Saenz Julienne
2023-12-05 15:02 ` Maxim Levitsky [this message]
2023-11-08 11:17 ` [RFC 07/33] KVM: x86: hyper-v: Introduce KVM_CAP_HYPERV_VSM Nicolas Saenz Julienne
2023-11-28 7:16 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 08/33] KVM: x86: Don't use hv_timer if CAP_HYPERV_VSM enabled Nicolas Saenz Julienne
2023-11-28 7:21 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 09/33] KVM: x86: hyper-v: Introduce per-VTL vcpu helpers Nicolas Saenz Julienne
2023-11-08 12:21 ` Alexander Graf
2023-11-08 14:04 ` Nicolas Saenz Julienne
2023-11-28 7:25 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 10/33] KVM: x86: hyper-v: Introduce KVM_HV_GET_VSM_STATE Nicolas Saenz Julienne
2023-11-28 7:26 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 11/33] KVM: x86: hyper-v: Handle GET/SET_VP_REGISTER hcall in user-space Nicolas Saenz Julienne
2023-11-08 12:14 ` Alexander Graf
2023-11-28 7:26 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 12/33] KVM: x86: hyper-v: Handle VSM hcalls " Nicolas Saenz Julienne
2023-11-28 7:28 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 13/33] KVM: Allow polling vCPUs for events Nicolas Saenz Julienne
2023-11-28 7:30 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 14/33] KVM: x86: Add VTL to the MMU role Nicolas Saenz Julienne
2023-11-08 17:26 ` Sean Christopherson
2023-11-10 18:52 ` Nicolas Saenz Julienne
2023-11-28 7:34 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 15/33] KVM: x86/mmu: Introduce infrastructure to handle non-executable faults Nicolas Saenz Julienne
2023-11-28 7:34 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 16/33] KVM: x86/mmu: Expose R/W/X flags during memory fault exits Nicolas Saenz Julienne
2023-11-28 7:36 ` Maxim Levitsky
2023-11-28 16:31 ` Sean Christopherson
2023-11-08 11:17 ` [RFC 17/33] KVM: x86/mmu: Allow setting memory attributes if VSM enabled Nicolas Saenz Julienne
2023-11-28 7:39 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 18/33] KVM: x86: Decouple kvm_get_memory_attributes() from struct kvm's mem_attr_array Nicolas Saenz Julienne
2023-11-08 16:59 ` Sean Christopherson
2023-11-28 7:41 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 19/33] KVM: x86: Decouple kvm_range_has_memory_attributes() " Nicolas Saenz Julienne
2023-11-28 7:42 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 20/33] KVM: x86/mmu: Decouple hugepage_has_attrs() " Nicolas Saenz Julienne
2023-11-28 7:43 ` Maxim Levitsky
2023-11-08 11:17 ` [RFC 21/33] KVM: Pass memory attribute array as a MMU notifier argument Nicolas Saenz Julienne
2023-11-08 17:08 ` Sean Christopherson
2023-11-08 11:17 ` [RFC 22/33] KVM: Decouple kvm_ioctl_set_mem_attributes() from kvm's mem_attr_array Nicolas Saenz Julienne
2023-11-08 11:17 ` [RFC 23/33] KVM: Expose memory attribute helper functions unanimously Nicolas Saenz Julienne
2023-11-08 11:17 ` [RFC 24/33] KVM: x86: hyper-v: Introduce KVM VTL device Nicolas Saenz Julienne
2023-11-08 11:17 ` [RFC 25/33] KVM: Introduce a set of new memory attributes Nicolas Saenz Julienne
2023-11-08 12:30 ` Alexander Graf
2023-11-08 16:43 ` Sean Christopherson
2023-11-08 11:17 ` [RFC 26/33] KVM: x86: hyper-vsm: Allow setting per-VTL " Nicolas Saenz Julienne
2023-11-28 7:44 ` Maxim Levitsky
2023-11-08 11:18 ` [RFC 27/33] KVM: x86/mmu/hyper-v: Validate memory faults against per-VTL memprots Nicolas Saenz Julienne
2023-11-28 7:46 ` Maxim Levitsky
2023-11-08 11:18 ` [RFC 28/33] x86/hyper-v: Introduce memory intercept message structure Nicolas Saenz Julienne
2023-11-28 7:53 ` Maxim Levitsky
2023-11-08 11:18 ` [RFC 29/33] KVM: VMX: Save instruction length on EPT violation Nicolas Saenz Julienne
2023-11-08 12:40 ` Alexander Graf
2023-11-08 16:15 ` Sean Christopherson
2023-11-08 17:11 ` Alexander Graf
2023-11-08 17:20 ` Sean Christopherson
2023-11-08 17:27 ` Alexander Graf
2023-11-08 18:19 ` Jim Mattson
2023-11-08 11:18 ` [RFC 30/33] KVM: x86: hyper-v: Introduce KVM_REQ_HV_INJECT_INTERCEPT request Nicolas Saenz Julienne
2023-11-08 12:45 ` Alexander Graf
2023-11-08 13:38 ` Nicolas Saenz Julienne
2023-11-28 8:19 ` Maxim Levitsky
2023-11-08 11:18 ` [RFC 31/33] KVM: x86: hyper-v: Inject intercept on VTL memory protection fault Nicolas Saenz Julienne
2023-11-08 11:18 ` [RFC 32/33] KVM: x86: hyper-v: Implement HVCALL_TRANSLATE_VIRTUAL_ADDRESS Nicolas Saenz Julienne
2023-11-08 12:49 ` Alexander Graf
2023-11-08 13:44 ` Nicolas Saenz Julienne
2023-11-08 11:18 ` [RFC 33/33] Documentation: KVM: Introduce "Emulating Hyper-V VSM with KVM" Nicolas Saenz Julienne
2023-11-28 8:19 ` Maxim Levitsky
2023-11-08 11:40 ` [RFC 0/33] KVM: x86: hyperv: Introduce VSM support Alexander Graf
2023-11-08 14:41 ` Nicolas Saenz Julienne
2023-11-08 16:55 ` Sean Christopherson
2023-11-08 18:33 ` Sean Christopherson
2023-11-10 17:56 ` Nicolas Saenz Julienne
2023-11-10 19:32 ` Sean Christopherson
2023-11-11 11:55 ` Nicolas Saenz Julienne
2023-11-10 19:04 ` Nicolas Saenz Julienne
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