KVM ARM Archive on lore.kernel.org
 help / color / Atom feed
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 8/9] KVM: arm/arm64: vgic-its: Check the LPI translation cache on MSI injection
Date: Wed, 24 Jul 2019 09:41:48 +0200
Message-ID: <1642a2fb-153b-070c-465d-fca27b76e3a0@redhat.com> (raw)
In-Reply-To: <3e3bf6bc-d1ab-ec77-e94c-d5defd133c5b@arm.com>

Hi Marc,

On 7/23/19 5:45 PM, Marc Zyngier wrote:
> Hi Eric,
> 
> On 23/07/2019 16:10, Auger Eric wrote:
>> Hi Marc,
>>
>> On 6/11/19 7:03 PM, Marc Zyngier wrote:
>>> When performing an MSI injection, let's first check if the translation
>>> is already in the cache. If so, let's inject it quickly without
>>> going through the whole translation process.
>>>
>>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>>> ---
>>>  virt/kvm/arm/vgic/vgic-its.c | 36 ++++++++++++++++++++++++++++++++++++
>>>  virt/kvm/arm/vgic/vgic.h     |  1 +
>>>  2 files changed, 37 insertions(+)
>>>
>>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>>> index 62932458476a..83d80ec33473 100644
>>> --- a/virt/kvm/arm/vgic/vgic-its.c
>>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>>> @@ -577,6 +577,20 @@ static struct vgic_irq *__vgic_its_check_cache(struct vgic_dist *dist,
>>>  	return irq;
>>>  }
>>>  
>>> +static struct vgic_irq *vgic_its_check_cache(struct kvm *kvm, phys_addr_t db,
>>> +					     u32 devid, u32 eventid)
>>> +{
>>> +	struct vgic_dist *dist = &kvm->arch.vgic;
>>> +	struct vgic_irq *irq;
>>> +	unsigned long flags;
>>> +
>>> +	raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
>>> +	irq = __vgic_its_check_cache(dist, db, devid, eventid);
>>> +	raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
>>> +
>>> +	return irq;
>>> +}
>>> +
>>>  static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
>>>  				       u32 devid, u32 eventid,
>>>  				       struct vgic_irq *irq)
>>> @@ -736,6 +750,25 @@ static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
>>>  	return 0;
>>>  }
>>>  
>>> +int vgic_its_inject_cached_translation(struct kvm *kvm, struct kvm_msi *msi)
>>> +{
>>> +	struct vgic_irq *irq;
>>> +	unsigned long flags;
>>> +	phys_addr_t db;
>>> +
>>> +	db = (u64)msi->address_hi << 32 | msi->address_lo;
>>> +	irq = vgic_its_check_cache(kvm, db, msi->devid, msi->data);
>>
>> I think we miss a check of its->enabled. This is currently done in
>> vgic_its_resolve_lpi() but now likely to be bypassed.
> 
> But why would a translation be cached if the ITS is disabled? It should
> never haver been there the first place (vgic_its_resolve_lpi does check
> for the ITS being enabled, as you pointed out).
> 
> Which makes me think that we miss an invalidate on an ITS being disabled:
> 
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index 2633b0e88981..5f2ad74ad834 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1719,6 +1719,8 @@ static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its,
>  		goto out;
>  
>  	its->enabled = !!(val & GITS_CTLR_ENABLE);
> +	if (!its->enabled)
> +		vgic_its_invalidate_cache(kvm);
>  
>  	/*
>  	 * Try to process any pending commands. This function bails out early
> 
> 
> What do you think?

Yes I agree this is the right way to fix it.

Thanks

Eric
> 
> 	M.
> 
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

  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
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 [this message]
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

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=1642a2fb-153b-070c-465d-fca27b76e3a0@redhat.com \
    --to=eric.auger@redhat.com \
    --cc=alisaidi@amazon.com \
    --cc=karahmed@amazon.de \
    --cc=kvm@vger.kernel.org \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=marc.zyngier@arm.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

KVM ARM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvmarm/0 kvmarm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvmarm kvmarm/ https://lore.kernel.org/kvmarm \
		kvmarm@lists.cs.columbia.edu kvmarm@archiver.kernel.org
	public-inbox-index kvmarm

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/edu.columbia.cs.lists.kvmarm


AGPL code for this site: git clone https://public-inbox.org/ public-inbox