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From: Dave Martin <Dave.Martin@arm.com>
To: Andre Przywara <andre.przywara@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>,
	kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 0/2] KVM: arm/arm64: Add VCPU workarounds firmware register
Date: Tue, 22 Jan 2019 10:17:00 +0000	[thread overview]
Message-ID: <20190122101657.GE3578@e103592.cambridge.arm.com> (raw)
In-Reply-To: <20190107120537.184252-1-andre.przywara@arm.com>

On Mon, Jan 07, 2019 at 12:05:35PM +0000, Andre Przywara wrote:
> Workarounds for Spectre variant 2 or 4 vulnerabilities require some help
> from the firmware, so KVM implements an interface to provide that for
> guests. When such a guest is migrated, we want to make sure we don't
> loose the protection the guest relies on.
> 
> This introduces two new firmware registers in KVM's GET/SET_ONE_REG
> interface, so userland can save the level of protection implemented by
> the hypervisor and used by the guest. Upon restoring these registers,
> we make sure we don't downgrade and reject any values that would mean
> weaker protection.

Just trolling here, but could we treat these as immutable, like the ID
registers?  

We don't support migration between nodes that are "too different" in any
case, so I wonder if adding complex logic to compare vulnerabilities and
workarounds is liable to create more problems than it solves...

Do we know of anyone who explicitly needs this flexibility yet?

[...]

Cheers
---Dave

WARNING: multiple messages have this Message-ID (diff)
From: Dave Martin <Dave.Martin@arm.com>
To: Andre Przywara <andre.przywara@arm.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>,
	kvm@vger.kernel.org, Christoffer Dall <christoffer.dall@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH 0/2] KVM: arm/arm64: Add VCPU workarounds firmware register
Date: Tue, 22 Jan 2019 10:17:00 +0000	[thread overview]
Message-ID: <20190122101657.GE3578@e103592.cambridge.arm.com> (raw)
In-Reply-To: <20190107120537.184252-1-andre.przywara@arm.com>

On Mon, Jan 07, 2019 at 12:05:35PM +0000, Andre Przywara wrote:
> Workarounds for Spectre variant 2 or 4 vulnerabilities require some help
> from the firmware, so KVM implements an interface to provide that for
> guests. When such a guest is migrated, we want to make sure we don't
> loose the protection the guest relies on.
> 
> This introduces two new firmware registers in KVM's GET/SET_ONE_REG
> interface, so userland can save the level of protection implemented by
> the hypervisor and used by the guest. Upon restoring these registers,
> we make sure we don't downgrade and reject any values that would mean
> weaker protection.

Just trolling here, but could we treat these as immutable, like the ID
registers?  

We don't support migration between nodes that are "too different" in any
case, so I wonder if adding complex logic to compare vulnerabilities and
workarounds is liable to create more problems than it solves...

Do we know of anyone who explicitly needs this flexibility yet?

[...]

Cheers
---Dave

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linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  parent reply	other threads:[~2019-01-22 10:17 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-07 12:05 [PATCH 0/2] KVM: arm/arm64: Add VCPU workarounds firmware register Andre Przywara
2019-01-07 12:05 ` Andre Przywara
2019-01-07 12:05 ` [PATCH 1/2] KVM: arm/arm64: Add save/restore support for firmware workaround state Andre Przywara
2019-01-07 12:05   ` Andre Przywara
2019-01-07 13:17   ` Steven Price
2019-01-07 13:17     ` Steven Price
2019-01-21 17:04     ` Andre Przywara
2019-01-21 17:04       ` Andre Przywara
2019-02-22 12:26     ` Andre Przywara
2019-02-22 12:26       ` Andre Przywara
2019-01-22 15:17   ` Dave Martin
2019-01-22 15:17     ` Dave Martin
2019-01-25 14:46     ` Andre Przywara
2019-01-25 14:46       ` Andre Przywara
2019-01-29 21:32       ` Dave Martin
2019-01-29 21:32         ` Dave Martin
2019-01-30 11:39         ` Andre Przywara
2019-01-30 11:39           ` Andre Przywara
2019-01-30 12:07           ` Dave Martin
2019-01-30 12:07             ` Dave Martin
2019-02-15  9:58           ` Andre Przywara
2019-02-15  9:58             ` Andre Przywara
2019-02-15 11:42             ` Marc Zyngier
2019-02-15 11:42               ` Marc Zyngier
2019-02-15 17:26               ` Dave Martin
2019-02-15 17:26                 ` Dave Martin
2019-02-18  9:07                 ` Marc Zyngier
2019-02-18  9:07                   ` Marc Zyngier
2019-02-18 10:28                   ` Dave Martin
2019-02-18 10:28                     ` Dave Martin
2019-02-18 10:59                     ` Marc Zyngier
2019-02-18 10:59                       ` Marc Zyngier
2019-02-18 11:29                   ` André Przywara
2019-02-18 11:29                     ` André Przywara
2019-02-18 14:15                     ` Marc Zyngier
2019-02-18 14:15                       ` Marc Zyngier
2019-01-07 12:05 ` [PATCH 2/2] KVM: doc: add API documentation on the KVM_REG_ARM_WORKAROUNDS register Andre Przywara
2019-01-07 12:05   ` Andre Przywara
2019-01-22 10:17 ` Dave Martin [this message]
2019-01-22 10:17   ` [PATCH 0/2] KVM: arm/arm64: Add VCPU workarounds firmware register Dave Martin
2019-01-22 10:41   ` Andre Przywara
2019-01-22 10:41     ` Andre Przywara
2019-01-22 11:11   ` Marc Zyngier
2019-01-22 11:11     ` Marc Zyngier
2019-01-22 13:56     ` Dave Martin
2019-01-22 13:56       ` Dave Martin
2019-01-22 14:51       ` Marc Zyngier
2019-01-22 14:51         ` Marc Zyngier
2019-01-22 15:28         ` Dave Martin
2019-01-22 15:28           ` Dave Martin

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