From: Auger Eric <eric.auger@redhat.com> To: Marc Zyngier <marc.zyngier@arm.com>, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Cc: "Raslan, KarimAllah" <karahmed@amazon.de>, "Saidi, Ali" <alisaidi@amazon.com> Subject: Re: [PATCH v2 4/9] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on specific commands Date: Tue, 23 Jul 2019 14:25:42 +0200 Message-ID: <8b5e029c-a08f-b86b-7021-5d68ec05d3bd@redhat.com> (raw) In-Reply-To: <1a78d52c-7a31-8981-230b-abe85d11b8ec@arm.com> Hi Marc, On 7/22/19 12:54 PM, Marc Zyngier wrote: > Hi Eric, > > On 01/07/2019 13:38, Auger Eric wrote: >> Hi Marc, >> >> On 6/11/19 7:03 PM, Marc Zyngier wrote: >>> The LPI translation cache needs to be discarded when an ITS command >>> may affect the translation of an LPI (DISCARD and MAPD with V=0) or >>> the routing of an LPI to a redistributor with disabled LPIs (MOVI, >>> MOVALL). >>> >>> We decide to perform a full invalidation of the cache, irrespective >>> of the LPI that is affected. Commands are supposed to be rare enough >>> that it doesn't matter. >>> >>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> >>> --- >>> virt/kvm/arm/vgic/vgic-its.c | 8 ++++++++ >>> 1 file changed, 8 insertions(+) >>> >>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c >>> index 9b6b66204b97..5254bb762e1b 100644 >>> --- a/virt/kvm/arm/vgic/vgic-its.c >>> +++ b/virt/kvm/arm/vgic/vgic-its.c >>> @@ -733,6 +733,8 @@ static int vgic_its_cmd_handle_discard(struct kvm *kvm, struct vgic_its *its, >>> * don't bother here since we clear the ITTE anyway and the >>> * pending state is a property of the ITTE struct. >>> */ >>> + vgic_its_invalidate_cache(kvm); >>> + >>> its_free_ite(kvm, ite); >>> return 0; >>> } >>> @@ -768,6 +770,8 @@ static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its, >>> ite->collection = collection; >>> vcpu = kvm_get_vcpu(kvm, collection->target_addr); >>> >>> + vgic_its_invalidate_cache(kvm); >>> + >>> return update_affinity(ite->irq, vcpu); >>> } >>> >>> @@ -996,6 +1000,8 @@ static void vgic_its_free_device(struct kvm *kvm, struct its_device *device) >>> list_for_each_entry_safe(ite, temp, &device->itt_head, ite_list) >>> its_free_ite(kvm, ite); >>> >>> + vgic_its_invalidate_cache(kvm); >>> + >>> list_del(&device->dev_list); >>> kfree(device); >>> } >>> @@ -1249,6 +1255,8 @@ static int vgic_its_cmd_handle_movall(struct kvm *kvm, struct vgic_its *its, >>> vgic_put_irq(kvm, irq); >>> } >>> >>> + vgic_its_invalidate_cache(kvm); >> All the commands are executed with the its_lock held. Now we don't take >> it anymore on the fast cache injection path. Don't we have a window >> where the move has been applied at table level and the cache is not yet >> invalidated? Same question for vgic_its_free_device(). > > There is definitely a race, but that race is invisible from the guest's > perspective. The guest can only assume that the command has taken effect > once a SYNC command has been executed, and it cannot observe that the > SYNC command has been executed before we have invalidated the cache. > > Does this answer your question? OK make sense. Thank you for the clarification Another question, don't we need to invalidate the cache on MAPC V=0 as well? Removing the mapping of the collection results in interrupts belonging to that collection being ignored. If we don't flush the pending bit will be set? Thanks Eric > > Thanks, > > M. > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
next prev parent reply index Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-06-11 17:03 [PATCH v2 0/9] KVM: arm/arm64: vgic: ITS translation cache Marc Zyngier 2019-06-11 17:03 ` [PATCH v2 1/9] KVM: arm/arm64: vgic: Add LPI translation cache definition Marc Zyngier 2019-06-12 8:16 ` Julien Thierry 2019-06-12 8:49 ` Julien Thierry 2019-06-12 9:52 ` Marc Zyngier 2019-06-12 10:58 ` Julien Thierry 2019-06-12 12:28 ` Julien Thierry 2019-07-23 12:43 ` Auger Eric 2019-06-11 17:03 ` [PATCH v2 2/9] KVM: arm/arm64: vgic: Add __vgic_put_lpi_locked primitive Marc Zyngier 2019-06-11 17:03 ` [PATCH v2 3/9] KVM: arm/arm64: vgic-its: Add MSI-LPI translation cache invalidation Marc Zyngier 2019-07-23 12:39 ` Auger Eric 2019-06-11 17:03 ` [PATCH v2 4/9] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on specific commands Marc Zyngier 2019-07-01 12:38 ` Auger Eric 2019-07-22 10:54 ` Marc Zyngier 2019-07-23 12:25 ` Auger Eric [this message] 2019-07-23 12:43 ` Marc Zyngier 2019-07-23 12:47 ` Auger Eric 2019-07-23 12:50 ` Marc Zyngier 2019-06-11 17:03 ` [PATCH v2 5/9] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on disabling LPIs Marc Zyngier 2019-07-23 15:09 ` Auger Eric 2019-06-11 17:03 ` [PATCH v2 6/9] KVM: arm/arm64: vgic-its: Invalidate MSI-LPI translation cache on vgic teardown Marc Zyngier 2019-07-23 15:10 ` Auger Eric 2019-06-11 17:03 ` [PATCH v2 7/9] KVM: arm/arm64: vgic-its: Cache successful MSI->LPI translation Marc Zyngier 2019-06-25 11:50 ` Zenghui Yu 2019-06-25 12:31 ` Marc Zyngier 2019-06-25 16:00 ` Zenghui Yu 2019-06-26 3:54 ` Zenghui Yu 2019-06-26 7:55 ` Marc Zyngier 2019-07-23 15:21 ` Auger Eric 2019-06-11 17:03 ` [PATCH v2 8/9] KVM: arm/arm64: vgic-its: Check the LPI translation cache on MSI injection Marc Zyngier 2019-07-23 15:10 ` Auger Eric 2019-07-23 15:45 ` Marc Zyngier 2019-07-24 7:41 ` Auger Eric 2019-06-11 17:03 ` [PATCH v2 9/9] KVM: arm/arm64: vgic-irqfd: Implement kvm_arch_set_irq_inatomic Marc Zyngier 2019-07-23 15:14 ` Auger Eric 2019-07-25 8:24 ` Marc Zyngier 2019-07-23 11:14 ` [PATCH v2 0/9] KVM: arm/arm64: vgic: ITS translation cache Andre Przywara 2019-07-25 8:50 ` Marc Zyngier 2019-07-25 10:01 ` Andre Przywara 2019-07-25 15:37 ` Marc Zyngier
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