From: Arnd Bergmann <arnd@arndb.de>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: linux-arm-kernel@lists.infradead.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Christoffer Dall <christoffer.dall@linaro.org>,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org
Subject: Re: [PATCH v2 00/21] arm64: Virtualization Host Extension support
Date: Mon, 25 Jan 2016 17:26:17 +0100 [thread overview]
Message-ID: <1602215.WjO3PgfQ53@wuerfel> (raw)
In-Reply-To: <56A64C09.4060702@arm.com>
On Monday 25 January 2016 16:23:37 Marc Zyngier wrote:
> On 25/01/16 16:15, Arnd Bergmann wrote:
> > On Monday 25 January 2016 15:53:34 Marc Zyngier wrote:
> >> host and guest, reducing the overhead of virtualization.
> >>
> >> In order to have the same kernel binary running on all versions of the
> >> architecture, this series makes heavy use of runtime code patching.
> >>
> >> The first 20 patches massage the KVM code to deal with VHE and enable
> >> Linux to run at EL2. The last patch catches an ugly case when VHE
> >> capable CPUs are paired with some of their less capable siblings. This
> >> should never happen, but hey...
> >>
> >> I have deliberately left out some of the more "advanced"
> >> optimizations, as they are likely to distract the reviewer from the
> >> core infrastructure, which is what I care about at the moment.
> >
> > One question: as you mention that you use a lot of runtime code patching
> > to make this work transparently, how does this compare to runtime patching
> > the existing kernel to run in EL2 mode without VHE? Is that even possible?
>
> I haven't explored that particular avenue - by the look of it, this
> would require a lot more work, as v8.0 EL2 lacks a number of features
> that Linux currently requires (like having two TTBRs, for example).
Ok, I see.
> > My interpretation so far as always been "that's too complicated to
> > do because it would require a lot of runtime patching", but now we seem
> > to get that anyway because we want to run a hypervisor-enabled kernel in
> > either EL1 or EL2 depending on the presence of another feature.
>
> The kernel itself is mostly untouched (what runs at EL1 also runs at EL2
> without any patching, because the new EL2 is now a superset of EL1). It
> is the hypervisor code that gets a beating with the code-patching stick.
Thanks for the explanation, makes sense.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: kvm@vger.kernel.org, Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v2 00/21] arm64: Virtualization Host Extension support
Date: Mon, 25 Jan 2016 17:26:17 +0100 [thread overview]
Message-ID: <1602215.WjO3PgfQ53@wuerfel> (raw)
In-Reply-To: <56A64C09.4060702@arm.com>
On Monday 25 January 2016 16:23:37 Marc Zyngier wrote:
> On 25/01/16 16:15, Arnd Bergmann wrote:
> > On Monday 25 January 2016 15:53:34 Marc Zyngier wrote:
> >> host and guest, reducing the overhead of virtualization.
> >>
> >> In order to have the same kernel binary running on all versions of the
> >> architecture, this series makes heavy use of runtime code patching.
> >>
> >> The first 20 patches massage the KVM code to deal with VHE and enable
> >> Linux to run at EL2. The last patch catches an ugly case when VHE
> >> capable CPUs are paired with some of their less capable siblings. This
> >> should never happen, but hey...
> >>
> >> I have deliberately left out some of the more "advanced"
> >> optimizations, as they are likely to distract the reviewer from the
> >> core infrastructure, which is what I care about at the moment.
> >
> > One question: as you mention that you use a lot of runtime code patching
> > to make this work transparently, how does this compare to runtime patching
> > the existing kernel to run in EL2 mode without VHE? Is that even possible?
>
> I haven't explored that particular avenue - by the look of it, this
> would require a lot more work, as v8.0 EL2 lacks a number of features
> that Linux currently requires (like having two TTBRs, for example).
Ok, I see.
> > My interpretation so far as always been "that's too complicated to
> > do because it would require a lot of runtime patching", but now we seem
> > to get that anyway because we want to run a hypervisor-enabled kernel in
> > either EL1 or EL2 depending on the presence of another feature.
>
> The kernel itself is mostly untouched (what runs at EL1 also runs at EL2
> without any patching, because the new EL2 is now a superset of EL1). It
> is the hypervisor code that gets a beating with the code-patching stick.
Thanks for the explanation, makes sense.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 00/21] arm64: Virtualization Host Extension support
Date: Mon, 25 Jan 2016 17:26:17 +0100 [thread overview]
Message-ID: <1602215.WjO3PgfQ53@wuerfel> (raw)
In-Reply-To: <56A64C09.4060702@arm.com>
On Monday 25 January 2016 16:23:37 Marc Zyngier wrote:
> On 25/01/16 16:15, Arnd Bergmann wrote:
> > On Monday 25 January 2016 15:53:34 Marc Zyngier wrote:
> >> host and guest, reducing the overhead of virtualization.
> >>
> >> In order to have the same kernel binary running on all versions of the
> >> architecture, this series makes heavy use of runtime code patching.
> >>
> >> The first 20 patches massage the KVM code to deal with VHE and enable
> >> Linux to run at EL2. The last patch catches an ugly case when VHE
> >> capable CPUs are paired with some of their less capable siblings. This
> >> should never happen, but hey...
> >>
> >> I have deliberately left out some of the more "advanced"
> >> optimizations, as they are likely to distract the reviewer from the
> >> core infrastructure, which is what I care about at the moment.
> >
> > One question: as you mention that you use a lot of runtime code patching
> > to make this work transparently, how does this compare to runtime patching
> > the existing kernel to run in EL2 mode without VHE? Is that even possible?
>
> I haven't explored that particular avenue - by the look of it, this
> would require a lot more work, as v8.0 EL2 lacks a number of features
> that Linux currently requires (like having two TTBRs, for example).
Ok, I see.
> > My interpretation so far as always been "that's too complicated to
> > do because it would require a lot of runtime patching", but now we seem
> > to get that anyway because we want to run a hypervisor-enabled kernel in
> > either EL1 or EL2 depending on the presence of another feature.
>
> The kernel itself is mostly untouched (what runs at EL1 also runs at EL2
> without any patching, because the new EL2 is now a superset of EL1). It
> is the hypervisor code that gets a beating with the code-patching stick.
Thanks for the explanation, makes sense.
Arnd
next prev parent reply other threads:[~2016-01-25 16:26 UTC|newest]
Thread overview: 232+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-25 15:53 [PATCH v2 00/21] arm64: Virtualization Host Extension support Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` [PATCH v2 01/21] arm/arm64: Add new is_kernel_in_hyp_mode predicate Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:59 ` Christoffer Dall
2016-02-01 13:59 ` Christoffer Dall
2016-02-01 13:59 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 02/21] arm64: Allow the arch timer to use the HYP timer Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 12:29 ` Christoffer Dall
2016-02-01 12:29 ` Christoffer Dall
2016-02-01 12:29 ` Christoffer Dall
2016-02-01 13:42 ` Marc Zyngier
2016-02-01 13:42 ` Marc Zyngier
2016-02-01 13:42 ` Marc Zyngier
2016-02-01 15:37 ` Christoffer Dall
2016-02-01 15:37 ` Christoffer Dall
2016-02-01 15:37 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 03/21] arm64: Add ARM64_HAS_VIRT_HOST_EXTN feature Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:59 ` Christoffer Dall
2016-02-01 13:59 ` Christoffer Dall
2016-02-01 13:59 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 04/21] arm64: KVM: Skip HYP setup when already running in HYP Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:59 ` Christoffer Dall
2016-02-01 13:59 ` Christoffer Dall
2016-02-01 13:59 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 05/21] arm64: KVM: VHE: Turn VTCR_EL2 setup into a reusable macro Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:13 ` Christoffer Dall
2016-02-01 13:13 ` Christoffer Dall
2016-02-01 13:13 ` Christoffer Dall
2016-02-01 14:21 ` Marc Zyngier
2016-02-01 14:21 ` Marc Zyngier
2016-02-01 14:21 ` Marc Zyngier
2016-02-01 15:38 ` Christoffer Dall
2016-02-01 15:38 ` Christoffer Dall
2016-02-01 15:38 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 06/21] arm64: KVM: VHE: Patch out use of HVC Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:16 ` Christoffer Dall
2016-02-01 13:16 ` Christoffer Dall
2016-02-01 13:34 ` Marc Zyngier
2016-02-01 13:34 ` Marc Zyngier
2016-02-01 15:36 ` Catalin Marinas
2016-02-01 15:36 ` Catalin Marinas
2016-02-01 15:36 ` Catalin Marinas
2016-02-01 16:20 ` Marc Zyngier
2016-02-01 16:20 ` Marc Zyngier
2016-02-01 16:20 ` Marc Zyngier
2016-02-01 17:08 ` Ard Biesheuvel
2016-02-01 17:08 ` Ard Biesheuvel
2016-02-01 17:08 ` Ard Biesheuvel
2016-02-01 17:28 ` Marc Zyngier
2016-02-01 17:28 ` Marc Zyngier
2016-02-01 17:28 ` Marc Zyngier
2016-02-02 15:42 ` Christoffer Dall
2016-02-02 15:42 ` Christoffer Dall
2016-02-02 15:42 ` Christoffer Dall
2016-02-01 15:39 ` Christoffer Dall
2016-02-01 15:39 ` Christoffer Dall
2016-02-01 15:39 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 07/21] arm64: KVM: VHE: Patch out kern_hyp_va Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:20 ` Christoffer Dall
2016-02-01 13:20 ` Christoffer Dall
2016-02-01 13:20 ` Christoffer Dall
2016-02-01 13:38 ` Marc Zyngier
2016-02-01 13:38 ` Marc Zyngier
2016-02-01 13:38 ` Marc Zyngier
2016-02-01 15:40 ` Christoffer Dall
2016-02-01 15:40 ` Christoffer Dall
2016-02-01 15:40 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 08/21] arm64: KVM: VHE: Introduce unified system register accessors Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:47 ` Christoffer Dall
2016-02-01 13:47 ` Christoffer Dall
2016-02-01 13:47 ` Christoffer Dall
2016-02-01 14:04 ` Marc Zyngier
2016-02-01 14:04 ` Marc Zyngier
2016-02-01 14:04 ` Marc Zyngier
2016-02-01 15:43 ` Christoffer Dall
2016-02-01 15:43 ` Christoffer Dall
2016-02-01 15:43 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 09/21] arm64: KVM: VHE: Differenciate host/guest sysreg save/restore Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:59 ` Christoffer Dall
2016-02-01 13:59 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 10/21] arm64: KVM: VHE: Split save/restore of sysregs shared between EL1 and EL2 Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:54 ` Christoffer Dall
2016-02-01 13:54 ` Christoffer Dall
2016-02-01 13:54 ` Christoffer Dall
2016-02-02 9:46 ` Marc Zyngier
2016-02-02 9:46 ` Marc Zyngier
2016-02-02 9:46 ` Marc Zyngier
2016-02-02 15:46 ` Christoffer Dall
2016-02-02 15:46 ` Christoffer Dall
2016-02-02 16:19 ` Marc Zyngier
2016-02-02 16:19 ` Marc Zyngier
2016-02-02 16:19 ` Marc Zyngier
2016-02-02 20:07 ` Christoffer Dall
2016-02-02 20:07 ` Christoffer Dall
2016-02-02 20:07 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 11/21] arm64: KVM: VHE: Use unified system register accessors Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 13:59 ` Christoffer Dall
2016-02-01 13:59 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 12/21] arm64: KVM: VHE: Enable minimal sysreg save/restore Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 14:02 ` Christoffer Dall
2016-02-01 14:02 ` Christoffer Dall
2016-02-01 14:02 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 13/21] arm64: KVM: VHE: Make __fpsimd_enabled VHE aware Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 14:17 ` Christoffer Dall
2016-02-01 14:17 ` Christoffer Dall
2016-02-01 14:17 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 14/21] arm64: KVM: VHE: Implement VHE activate/deactivate_traps Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 14:20 ` Christoffer Dall
2016-02-01 14:20 ` Christoffer Dall
2016-02-01 14:20 ` Christoffer Dall
2016-02-02 11:27 ` Marc Zyngier
2016-02-02 11:27 ` Marc Zyngier
2016-01-25 15:53 ` [PATCH v2 15/21] arm64: KVM: VHE: Use unified sysreg accessors for timer Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 14:23 ` Christoffer Dall
2016-02-01 14:23 ` Christoffer Dall
2016-02-01 14:23 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 16/21] arm64: KVM: VHE: Add fpsimd enabling on guest access Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 14:24 ` Christoffer Dall
2016-02-01 14:24 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 17/21] arm64: KVM: VHE: Add alternative panic handling Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 14:26 ` Christoffer Dall
2016-02-01 14:26 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 18/21] arm64: KVM: Introduce hyp_alternate_value helper Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 14:41 ` Christoffer Dall
2016-02-01 14:41 ` Christoffer Dall
2016-02-02 13:42 ` Marc Zyngier
2016-02-02 13:42 ` Marc Zyngier
2016-02-02 15:47 ` Christoffer Dall
2016-02-02 15:47 ` Christoffer Dall
2016-02-02 15:47 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 19/21] arm64: KVM: Move most of the fault decoding to C Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-02-01 15:21 ` Christoffer Dall
2016-02-01 15:21 ` Christoffer Dall
2016-02-01 15:21 ` Christoffer Dall
2016-02-02 14:24 ` Marc Zyngier
2016-02-02 14:24 ` Marc Zyngier
2016-02-02 14:24 ` Marc Zyngier
2016-02-02 15:50 ` Christoffer Dall
2016-02-02 15:50 ` Christoffer Dall
2016-02-02 15:50 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 20/21] arm64: VHE: Add support for running Linux in EL2 mode Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-26 14:04 ` Suzuki K. Poulose
2016-01-26 14:04 ` Suzuki K. Poulose
2016-01-26 14:30 ` Suzuki K. Poulose
2016-01-26 14:30 ` Suzuki K. Poulose
2016-02-01 15:26 ` Christoffer Dall
2016-02-01 15:26 ` Christoffer Dall
2016-01-25 15:53 ` [PATCH v2 21/21] arm64: Panic when VHE and non VHE CPUs coexist Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-25 15:53 ` Marc Zyngier
2016-01-26 14:25 ` Suzuki K. Poulose
2016-01-26 14:25 ` Suzuki K. Poulose
2016-01-26 14:25 ` Suzuki K. Poulose
2016-01-26 14:34 ` Marc Zyngier
2016-01-26 14:34 ` Marc Zyngier
2016-01-26 14:34 ` Marc Zyngier
2016-02-01 15:36 ` Christoffer Dall
2016-02-01 15:36 ` Christoffer Dall
2016-02-01 15:36 ` Christoffer Dall
2016-02-02 15:32 ` Marc Zyngier
2016-02-02 15:32 ` Marc Zyngier
2016-02-03 8:49 ` Christoffer Dall
2016-02-03 8:49 ` Christoffer Dall
2016-02-03 8:49 ` Christoffer Dall
2016-02-03 17:45 ` Marc Zyngier
2016-02-03 17:45 ` Marc Zyngier
2016-02-03 17:45 ` Marc Zyngier
2016-02-03 19:12 ` Christoffer Dall
2016-02-03 19:12 ` Christoffer Dall
2016-02-03 19:12 ` Christoffer Dall
2016-01-25 16:15 ` [PATCH v2 00/21] arm64: Virtualization Host Extension support Arnd Bergmann
2016-01-25 16:15 ` Arnd Bergmann
2016-01-25 16:15 ` Arnd Bergmann
2016-01-25 16:23 ` Marc Zyngier
2016-01-25 16:23 ` Marc Zyngier
2016-01-25 16:26 ` Arnd Bergmann [this message]
2016-01-25 16:26 ` Arnd Bergmann
2016-01-25 16:26 ` Arnd Bergmann
2016-01-25 16:26 ` Will Deacon
2016-01-25 16:26 ` Will Deacon
2016-01-25 16:26 ` Will Deacon
2016-01-25 16:37 ` Marc Zyngier
2016-01-25 16:37 ` Marc Zyngier
2016-01-25 16:37 ` Marc Zyngier
2016-01-25 16:44 ` Will Deacon
2016-01-25 16:44 ` Will Deacon
2016-01-25 19:16 ` Marc Zyngier
2016-01-25 19:16 ` Marc Zyngier
2016-01-25 19:16 ` Marc Zyngier
2016-02-01 16:25 ` Christoffer Dall
2016-02-01 16:25 ` Christoffer Dall
2016-02-01 16:25 ` Christoffer Dall
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