From: Christoffer Dall <christoffer.dall@linaro.org>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Catalin Marinas <catalin.marinas@arm.com>,
KVM devel mailing list <kvm@vger.kernel.org>,
Will Deacon <will.deacon@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 06/21] arm64: KVM: VHE: Patch out use of HVC
Date: Tue, 2 Feb 2016 16:42:12 +0100 [thread overview]
Message-ID: <20160202154212.GD6190@cbox> (raw)
In-Reply-To: <56AF95C0.3080006@arm.com>
On Mon, Feb 01, 2016 at 05:28:32PM +0000, Marc Zyngier wrote:
> On 01/02/16 17:08, Ard Biesheuvel wrote:
> > On 1 February 2016 at 17:20, Marc Zyngier <marc.zyngier@arm.com> wrote:
> >> On 01/02/16 15:36, Catalin Marinas wrote:
> >>> On Mon, Feb 01, 2016 at 01:34:16PM +0000, Marc Zyngier wrote:
> >>>> On 01/02/16 13:16, Christoffer Dall wrote:
> >>>>> On Mon, Jan 25, 2016 at 03:53:40PM +0000, Marc Zyngier wrote:
> >>>>>> diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
> >>>>>> index 93e8d983..9e0683f 100644
> >>>>>> --- a/arch/arm64/kvm/hyp/hyp-entry.S
> >>>>>> +++ b/arch/arm64/kvm/hyp/hyp-entry.S
> >>>>>> @@ -38,6 +38,32 @@
> >>>>>> ldp x0, x1, [sp], #16
> >>>>>> .endm
> >>>>>>
> >>>>>> +.macro do_el2_call
> >>>>>> + /*
> >>>>>> + * Shuffle the parameters before calling the function
> >>>>>> + * pointed to in x0. Assumes parameters in x[1,2,3].
> >>>>>> + */
> >>>>>> + stp lr, xzr, [sp, #-16]!
> >>>>>
> >>>>> remind me why this pair isn't just doing "str" instead of "stp" with the
> >>>>> xzr ?
> >>>>
> >>>> Because SP has to be aligned on a 16 bytes boundary at all times.
> >>>
> >>> You could do something like:
> >>>
> >>> sub sp, sp, #16
> >>> str lr, [sp]
> >>>
> >>
> >> Ah, fair enough. I'll fold that in.
> >>
> >
> > Since we're micro-reviewing: what's wrong with
> >
> > str lr, [sp, #-16]!
> >
> > ?
> >
>
> I suspect that on most micro-architectures, a register writeback is
> going to be slower than doing the sub independently.
>
> I may be wrong, though.
>
For the record, I don't mind it the way it was in the original patch
either, I was just curious about the store of xzr and had forgottten the
stack alignment thing.
-Christoffer
WARNING: multiple messages have this Message-ID (diff)
From: christoffer.dall@linaro.org (Christoffer Dall)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 06/21] arm64: KVM: VHE: Patch out use of HVC
Date: Tue, 2 Feb 2016 16:42:12 +0100 [thread overview]
Message-ID: <20160202154212.GD6190@cbox> (raw)
In-Reply-To: <56AF95C0.3080006@arm.com>
On Mon, Feb 01, 2016 at 05:28:32PM +0000, Marc Zyngier wrote:
> On 01/02/16 17:08, Ard Biesheuvel wrote:
> > On 1 February 2016 at 17:20, Marc Zyngier <marc.zyngier@arm.com> wrote:
> >> On 01/02/16 15:36, Catalin Marinas wrote:
> >>> On Mon, Feb 01, 2016 at 01:34:16PM +0000, Marc Zyngier wrote:
> >>>> On 01/02/16 13:16, Christoffer Dall wrote:
> >>>>> On Mon, Jan 25, 2016 at 03:53:40PM +0000, Marc Zyngier wrote:
> >>>>>> diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
> >>>>>> index 93e8d983..9e0683f 100644
> >>>>>> --- a/arch/arm64/kvm/hyp/hyp-entry.S
> >>>>>> +++ b/arch/arm64/kvm/hyp/hyp-entry.S
> >>>>>> @@ -38,6 +38,32 @@
> >>>>>> ldp x0, x1, [sp], #16
> >>>>>> .endm
> >>>>>>
> >>>>>> +.macro do_el2_call
> >>>>>> + /*
> >>>>>> + * Shuffle the parameters before calling the function
> >>>>>> + * pointed to in x0. Assumes parameters in x[1,2,3].
> >>>>>> + */
> >>>>>> + stp lr, xzr, [sp, #-16]!
> >>>>>
> >>>>> remind me why this pair isn't just doing "str" instead of "stp" with the
> >>>>> xzr ?
> >>>>
> >>>> Because SP has to be aligned on a 16 bytes boundary at all times.
> >>>
> >>> You could do something like:
> >>>
> >>> sub sp, sp, #16
> >>> str lr, [sp]
> >>>
> >>
> >> Ah, fair enough. I'll fold that in.
> >>
> >
> > Since we're micro-reviewing: what's wrong with
> >
> > str lr, [sp, #-16]!
> >
> > ?
> >
>
> I suspect that on most micro-architectures, a register writeback is
> going to be slower than doing the sub independently.
>
> I may be wrong, though.
>
For the record, I don't mind it the way it was in the original patch
either, I was just curious about the store of xzr and had forgottten the
stack alignment thing.
-Christoffer
next prev parent reply other threads:[~2016-02-02 15:42 UTC|newest]
Thread overview: 231+ 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 [this message]
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
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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