From: Marc Zyngier <maz@kernel.org>
To: James Morse <james.morse@arm.com>
Cc: Julien Grall <julien@xen.org>,
kvm@vger.kernel.org, Andre Przywara <Andre.Przywara@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 4/6] KVM: arm: vgic-v2: Only use the virtual state when userspace accesses pending bits
Date: Wed, 22 Apr 2020 17:02:30 +0100 [thread overview]
Message-ID: <299b5f1307cff29944e5f89e307b2015@kernel.org> (raw)
In-Reply-To: <5aa2acf8-e775-325c-0340-fa000a4e3513@arm.com>
Hi James,
On 2020-04-22 16:55, James Morse wrote:
> Hi Marc,
>
> On 20/04/2020 11:03, Marc Zyngier wrote:
>> On Fri, 17 Apr 2020 17:48:34 +0100
>> James Morse <james.morse@arm.com> wrote:
[...]
>>> (but if user-space never actually does this, then we should do the
>>> simplest thing)
>
> Adding printk() to this combined patch and using 'loadvm' on the qemu
> console, I see Qemu
> writing '0xffffffff' into cpending to clear all 16 SGIs. I guess it is
> 'resetting' the
> in-kernel state to replace it with the state read from disk.
>
>
>> A third way would be to align on what GICv3 does, which is that
>> ISPENDR
>> is used for both setting and clearing in one go. Given that the
>> current
>> state it broken (and has been for some time now), I'm tempted to adopt
>> the same behaviour...
>
>> What do you think?
>
> I think Qemu is expecting the bank of cpending writes to clear
> whatever the kernel has
> stored, so that it can replay the new state. Ignoring the cpending
> writes means the kernel
> keeps an interrupt pending if nothing else in that 64bit group was
> set. Its not what Qemu
> expects, it looks like we'd get away with it, but I don't think we
> should do it!
>
> I think we should let user-space write to those WI registers, and
> clearing the SGIs should clear all sources of SGI...
I'd be happy with that. Let me rework the patch, and I'll post the
series again
shortly.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: James Morse <james.morse@arm.com>
Cc: Julien Grall <julien@xen.org>,
kvm@vger.kernel.org, Suzuki K Poulose <suzuki.poulose@arm.com>,
Andre Przywara <Andre.Przywara@arm.com>,
Eric Auger <eric.auger@redhat.com>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Zenghui Yu <yuzenghui@huawei.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 4/6] KVM: arm: vgic-v2: Only use the virtual state when userspace accesses pending bits
Date: Wed, 22 Apr 2020 17:02:30 +0100 [thread overview]
Message-ID: <299b5f1307cff29944e5f89e307b2015@kernel.org> (raw)
In-Reply-To: <5aa2acf8-e775-325c-0340-fa000a4e3513@arm.com>
Hi James,
On 2020-04-22 16:55, James Morse wrote:
> Hi Marc,
>
> On 20/04/2020 11:03, Marc Zyngier wrote:
>> On Fri, 17 Apr 2020 17:48:34 +0100
>> James Morse <james.morse@arm.com> wrote:
[...]
>>> (but if user-space never actually does this, then we should do the
>>> simplest thing)
>
> Adding printk() to this combined patch and using 'loadvm' on the qemu
> console, I see Qemu
> writing '0xffffffff' into cpending to clear all 16 SGIs. I guess it is
> 'resetting' the
> in-kernel state to replace it with the state read from disk.
>
>
>> A third way would be to align on what GICv3 does, which is that
>> ISPENDR
>> is used for both setting and clearing in one go. Given that the
>> current
>> state it broken (and has been for some time now), I'm tempted to adopt
>> the same behaviour...
>
>> What do you think?
>
> I think Qemu is expecting the bank of cpending writes to clear
> whatever the kernel has
> stored, so that it can replay the new state. Ignoring the cpending
> writes means the kernel
> keeps an interrupt pending if nothing else in that 64bit group was
> set. Its not what Qemu
> expects, it looks like we'd get away with it, but I don't think we
> should do it!
>
> I think we should let user-space write to those WI registers, and
> clearing the SGIs should clear all sources of SGI...
I'd be happy with that. Let me rework the patch, and I'll post the
series again
shortly.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
WARNING: multiple messages have this Message-ID (diff)
From: Marc Zyngier <maz@kernel.org>
To: James Morse <james.morse@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
Zenghui Yu <yuzenghui@huawei.com>,
Eric Auger <eric.auger@redhat.com>,
Andre Przywara <Andre.Przywara@arm.com>,
Julien Grall <julien@xen.org>,
Julien Thierry <julien.thierry.kdev@gmail.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: Re: [PATCH v2 4/6] KVM: arm: vgic-v2: Only use the virtual state when userspace accesses pending bits
Date: Wed, 22 Apr 2020 17:02:30 +0100 [thread overview]
Message-ID: <299b5f1307cff29944e5f89e307b2015@kernel.org> (raw)
In-Reply-To: <5aa2acf8-e775-325c-0340-fa000a4e3513@arm.com>
Hi James,
On 2020-04-22 16:55, James Morse wrote:
> Hi Marc,
>
> On 20/04/2020 11:03, Marc Zyngier wrote:
>> On Fri, 17 Apr 2020 17:48:34 +0100
>> James Morse <james.morse@arm.com> wrote:
[...]
>>> (but if user-space never actually does this, then we should do the
>>> simplest thing)
>
> Adding printk() to this combined patch and using 'loadvm' on the qemu
> console, I see Qemu
> writing '0xffffffff' into cpending to clear all 16 SGIs. I guess it is
> 'resetting' the
> in-kernel state to replace it with the state read from disk.
>
>
>> A third way would be to align on what GICv3 does, which is that
>> ISPENDR
>> is used for both setting and clearing in one go. Given that the
>> current
>> state it broken (and has been for some time now), I'm tempted to adopt
>> the same behaviour...
>
>> What do you think?
>
> I think Qemu is expecting the bank of cpending writes to clear
> whatever the kernel has
> stored, so that it can replay the new state. Ignoring the cpending
> writes means the kernel
> keeps an interrupt pending if nothing else in that 64bit group was
> set. Its not what Qemu
> expects, it looks like we'd get away with it, but I don't think we
> should do it!
>
> I think we should let user-space write to those WI registers, and
> clearing the SGIs should clear all sources of SGI...
I'd be happy with that. Let me rework the patch, and I'll post the
series again
shortly.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2020-04-22 16:02 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-17 8:33 [PATCH v2 0/6] KVM: arm: vgic fixes for 5.7 Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 8:33 ` [PATCH v2 1/6] KVM: arm: vgic: Fix limit condition when writing to GICD_I[CS]ACTIVER Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 8:33 ` [PATCH v2 2/6] KVM: arm: vgic: Synchronize the whole guest on GIC{D, R}_I{S, C}ACTIVER read Marc Zyngier
2020-04-17 8:33 ` [PATCH v2 2/6] KVM: arm: vgic: Synchronize the whole guest on GIC{D,R}_I{S,C}ACTIVER read Marc Zyngier
2020-04-17 8:33 ` [PATCH v2 2/6] KVM: arm: vgic: Synchronize the whole guest on GIC{D, R}_I{S, C}ACTIVER read Marc Zyngier
2020-04-17 16:26 ` [PATCH v2 2/6] KVM: arm: vgic: Synchronize the whole guest on GIC{D,R}_I{S,C}ACTIVER read André Przywara
2020-04-17 16:26 ` André Przywara
2020-04-17 16:26 ` André Przywara
2020-04-17 8:33 ` [PATCH v2 3/6] KVM: arm: vgic: Only use the virtual state when userspace accesses enable bits Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 11:17 ` James Morse
2020-04-17 11:17 ` James Morse
2020-04-17 11:17 ` James Morse
2020-04-17 8:33 ` [PATCH v2 4/6] KVM: arm: vgic-v2: Only use the virtual state when userspace accesses pending bits Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 11:22 ` James Morse
2020-04-17 11:22 ` James Morse
2020-04-17 11:22 ` James Morse
2020-04-17 12:41 ` Marc Zyngier
2020-04-17 12:41 ` Marc Zyngier
2020-04-17 12:41 ` Marc Zyngier
2020-04-17 16:48 ` James Morse
2020-04-17 16:48 ` James Morse
2020-04-17 16:48 ` James Morse
2020-04-20 10:03 ` Marc Zyngier
2020-04-20 10:03 ` Marc Zyngier
2020-04-20 10:03 ` Marc Zyngier
2020-04-22 15:55 ` James Morse
2020-04-22 15:55 ` James Morse
2020-04-22 15:55 ` James Morse
2020-04-22 16:02 ` Marc Zyngier [this message]
2020-04-22 16:02 ` Marc Zyngier
2020-04-22 16:02 ` Marc Zyngier
2020-04-17 8:33 ` [PATCH v2 5/6] KVM: arm64: vgic-v3: Retire all pending LPIs on vcpu destroy Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 8:33 ` [PATCH v2 6/6] KVM: arm64: vgic-its: Fix memory leak on the error path of vgic_add_lpi() Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
2020-04-17 8:33 ` Marc Zyngier
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