From: Dave Martin <Dave.Martin@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arch@vger.kernel.org, libc-alpha@sourceware.org,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Szabolcs Nagy <szabolcs.nagy@arm.com>,
Richard Sandiford <richard.sandiford@arm.com>,
Will Deacon <will.deacon@arm.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 10/28] arm64/sve: Low-level CPU setup
Date: Wed, 13 Sep 2017 20:21:11 +0100 [thread overview]
Message-ID: <20170913192110.GE23415@e103592.cambridge.arm.com> (raw)
In-Reply-To: <20170913133206.rwobtu7ft5nrsh4p@localhost>
On Wed, Sep 13, 2017 at 06:32:06AM -0700, Catalin Marinas wrote:
> On Thu, Aug 31, 2017 at 06:00:42PM +0100, Dave P Martin wrote:
> > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
> > index 877d42f..dd22ef2 100644
> > --- a/arch/arm64/mm/proc.S
> > +++ b/arch/arm64/mm/proc.S
> > @@ -27,6 +27,7 @@
> > #include <asm/pgtable-hwdef.h>
> > #include <asm/cpufeature.h>
> > #include <asm/alternative.h>
> > +#include <asm/sysreg.h>
> >
> > #ifdef CONFIG_ARM64_64K_PAGES
> > #define TCR_TG_FLAGS TCR_TG0_64K | TCR_TG1_64K
> > @@ -186,8 +187,17 @@ ENTRY(__cpu_setup)
> > tlbi vmalle1 // Invalidate local TLB
> > dsb nsh
> >
> > - mov x0, #3 << 20
> > - msr cpacr_el1, x0 // Enable FP/ASIMD
> > + mov x0, #3 << 20 // FEN
> > +
> > + /* SVE */
> > + mrs x5, id_aa64pfr0_el1
> > + ubfx x5, x5, #ID_AA64PFR0_SVE_SHIFT, #4
> > + cbz x5, 1f
> > +
> > + bic x0, x0, #CPACR_EL1_ZEN
> > + orr x0, x0, #CPACR_EL1_ZEN_EL1EN // SVE: trap for EL0, not EL1
> > +1: msr cpacr_el1, x0 // Enable FP/ASIMD
>
> For EL1, I wonder whether we could move this later to cpufeature.c. IIRC
> I tried to do the same with FPSIMD but hit an issue with EFI run-time
> services (I may be wrong though).
I'll take a look at this -- I believe it should be safe to disable this
trap for EL1 relatively late. This is needed before probing for
available vector lengths, but apart from that the kernel shouldn't touch
SVE until/unless some user task uses SVE.
This would change if we eventually enable kernel-mode SVE, but I wouldn't
expect that to get used in early boot before the cpufeatures code runs.
Ard may have a view on this.
Cheers
---Dave
WARNING: multiple messages have this Message-ID (diff)
From: Dave Martin <Dave.Martin@arm.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arch@vger.kernel.org, libc-alpha@sourceware.org,
"Ard Biesheuvel" <ard.biesheuvel@linaro.org>,
"Szabolcs Nagy" <szabolcs.nagy@arm.com>,
"Richard Sandiford" <richard.sandiford@arm.com>,
"Will Deacon" <will.deacon@arm.com>,
"Alex Bennée" <alex.bennee@linaro.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 10/28] arm64/sve: Low-level CPU setup
Date: Wed, 13 Sep 2017 20:21:11 +0100 [thread overview]
Message-ID: <20170913192110.GE23415@e103592.cambridge.arm.com> (raw)
Message-ID: <20170913192111.9qMoKmAvPwSaph0-90P_7fOOU5HgzTGasuJHDXFjWAc@z> (raw)
In-Reply-To: <20170913133206.rwobtu7ft5nrsh4p@localhost>
On Wed, Sep 13, 2017 at 06:32:06AM -0700, Catalin Marinas wrote:
> On Thu, Aug 31, 2017 at 06:00:42PM +0100, Dave P Martin wrote:
> > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
> > index 877d42f..dd22ef2 100644
> > --- a/arch/arm64/mm/proc.S
> > +++ b/arch/arm64/mm/proc.S
> > @@ -27,6 +27,7 @@
> > #include <asm/pgtable-hwdef.h>
> > #include <asm/cpufeature.h>
> > #include <asm/alternative.h>
> > +#include <asm/sysreg.h>
> >
> > #ifdef CONFIG_ARM64_64K_PAGES
> > #define TCR_TG_FLAGS TCR_TG0_64K | TCR_TG1_64K
> > @@ -186,8 +187,17 @@ ENTRY(__cpu_setup)
> > tlbi vmalle1 // Invalidate local TLB
> > dsb nsh
> >
> > - mov x0, #3 << 20
> > - msr cpacr_el1, x0 // Enable FP/ASIMD
> > + mov x0, #3 << 20 // FEN
> > +
> > + /* SVE */
> > + mrs x5, id_aa64pfr0_el1
> > + ubfx x5, x5, #ID_AA64PFR0_SVE_SHIFT, #4
> > + cbz x5, 1f
> > +
> > + bic x0, x0, #CPACR_EL1_ZEN
> > + orr x0, x0, #CPACR_EL1_ZEN_EL1EN // SVE: trap for EL0, not EL1
> > +1: msr cpacr_el1, x0 // Enable FP/ASIMD
>
> For EL1, I wonder whether we could move this later to cpufeature.c. IIRC
> I tried to do the same with FPSIMD but hit an issue with EFI run-time
> services (I may be wrong though).
I'll take a look at this -- I believe it should be safe to disable this
trap for EL1 relatively late. This is needed before probing for
available vector lengths, but apart from that the kernel shouldn't touch
SVE until/unless some user task uses SVE.
This would change if we eventually enable kernel-mode SVE, but I wouldn't
expect that to get used in early boot before the cpufeatures code runs.
Ard may have a view on this.
Cheers
---Dave
WARNING: multiple messages have this Message-ID (diff)
From: Dave.Martin@arm.com (Dave Martin)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v2 10/28] arm64/sve: Low-level CPU setup
Date: Wed, 13 Sep 2017 20:21:11 +0100 [thread overview]
Message-ID: <20170913192110.GE23415@e103592.cambridge.arm.com> (raw)
In-Reply-To: <20170913133206.rwobtu7ft5nrsh4p@localhost>
On Wed, Sep 13, 2017 at 06:32:06AM -0700, Catalin Marinas wrote:
> On Thu, Aug 31, 2017 at 06:00:42PM +0100, Dave P Martin wrote:
> > diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S
> > index 877d42f..dd22ef2 100644
> > --- a/arch/arm64/mm/proc.S
> > +++ b/arch/arm64/mm/proc.S
> > @@ -27,6 +27,7 @@
> > #include <asm/pgtable-hwdef.h>
> > #include <asm/cpufeature.h>
> > #include <asm/alternative.h>
> > +#include <asm/sysreg.h>
> >
> > #ifdef CONFIG_ARM64_64K_PAGES
> > #define TCR_TG_FLAGS TCR_TG0_64K | TCR_TG1_64K
> > @@ -186,8 +187,17 @@ ENTRY(__cpu_setup)
> > tlbi vmalle1 // Invalidate local TLB
> > dsb nsh
> >
> > - mov x0, #3 << 20
> > - msr cpacr_el1, x0 // Enable FP/ASIMD
> > + mov x0, #3 << 20 // FEN
> > +
> > + /* SVE */
> > + mrs x5, id_aa64pfr0_el1
> > + ubfx x5, x5, #ID_AA64PFR0_SVE_SHIFT, #4
> > + cbz x5, 1f
> > +
> > + bic x0, x0, #CPACR_EL1_ZEN
> > + orr x0, x0, #CPACR_EL1_ZEN_EL1EN // SVE: trap for EL0, not EL1
> > +1: msr cpacr_el1, x0 // Enable FP/ASIMD
>
> For EL1, I wonder whether we could move this later to cpufeature.c. IIRC
> I tried to do the same with FPSIMD but hit an issue with EFI run-time
> services (I may be wrong though).
I'll take a look at this -- I believe it should be safe to disable this
trap for EL1 relatively late. This is needed before probing for
available vector lengths, but apart from that the kernel shouldn't touch
SVE until/unless some user task uses SVE.
This would change if we eventually enable kernel-mode SVE, but I wouldn't
expect that to get used in early boot before the cpufeatures code runs.
Ard may have a view on this.
Cheers
---Dave
next prev parent reply other threads:[~2017-09-13 19:21 UTC|newest]
Thread overview: 224+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-31 17:00 [PATCH v2 00/28] ARM Scalable Vector Extension (SVE) Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 01/28] regset: Add support for dynamically sized regsets Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 02/28] arm64: KVM: Hide unsupported AArch64 CPU features from guests Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-13 14:37 ` Alex Bennée
2017-09-13 14:37 ` Alex Bennée
2017-09-13 14:37 ` Alex Bennée
2017-09-15 0:04 ` Dave Martin
2017-09-15 0:04 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 03/28] arm64: efi: Add missing Kconfig dependency on KERNEL_MODE_NEON Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 04/28] arm64: Port deprecated instruction emulation to new sysctl interface Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 05/28] arm64: fpsimd: Simplify uses of {set,clear}_ti_thread_flag() Dave Martin
2017-08-31 17:00 ` [PATCH v2 05/28] arm64: fpsimd: Simplify uses of {set, clear}_ti_thread_flag() Dave Martin
2017-08-31 17:00 ` [PATCH v2 06/28] arm64/sve: System register and exception syndrome definitions Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-13 14:48 ` Alex Bennée
2017-09-13 14:48 ` Alex Bennée
2017-09-13 14:48 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 07/28] arm64/sve: Low-level SVE architectural state manipulation functions Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-13 15:39 ` Alex Bennée
2017-09-13 15:39 ` Alex Bennée
2017-09-13 15:39 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 08/28] arm64/sve: Kconfig update and conditional compilation support Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 09/28] arm64/sve: Signal frame and context structure definition Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-13 13:36 ` Catalin Marinas
2017-09-13 13:36 ` Catalin Marinas
2017-09-13 21:33 ` Dave Martin
2017-09-13 21:33 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 10/28] arm64/sve: Low-level CPU setup Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-13 13:32 ` Catalin Marinas
2017-09-13 13:32 ` Catalin Marinas
2017-09-13 19:21 ` Dave Martin [this message]
2017-09-13 19:21 ` Dave Martin
2017-09-13 19:21 ` Dave Martin
2017-10-05 10:47 ` Dave Martin
2017-10-05 10:47 ` Dave Martin
2017-10-05 11:04 ` Suzuki K Poulose
2017-10-05 11:04 ` Suzuki K Poulose
2017-10-05 11:22 ` Dave Martin
2017-10-05 11:22 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 11/28] arm64/sve: Core task context handling Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-13 14:33 ` Catalin Marinas
2017-09-13 14:33 ` Catalin Marinas
2017-09-14 19:55 ` Dave Martin
2017-09-14 19:55 ` Dave Martin
2017-09-20 13:58 ` Catalin Marinas
2017-09-20 13:58 ` Catalin Marinas
2017-10-03 11:11 ` Dave Martin
2017-10-03 11:11 ` Dave Martin
2017-10-04 17:29 ` Catalin Marinas
2017-10-04 17:29 ` Catalin Marinas
2017-10-03 11:33 ` Dave Martin
2017-10-03 11:33 ` Dave Martin
2017-10-05 11:28 ` Catalin Marinas
2017-10-05 11:28 ` Catalin Marinas
2017-10-06 13:10 ` Dave Martin
2017-10-06 13:10 ` Dave Martin
2017-10-06 13:36 ` Catalin Marinas
2017-10-06 13:36 ` Catalin Marinas
2017-10-06 15:15 ` Dave Martin
2017-10-06 15:15 ` Dave Martin
2017-10-06 15:33 ` Catalin Marinas
2017-10-06 15:33 ` Catalin Marinas
2017-09-13 17:26 ` Catalin Marinas
2017-09-13 17:26 ` Catalin Marinas
2017-09-13 19:17 ` Dave Martin
2017-09-13 19:17 ` Dave Martin
2017-09-13 22:21 ` Catalin Marinas
2017-09-13 22:21 ` Catalin Marinas
2017-09-14 19:40 ` Dave Martin
2017-09-14 19:40 ` Dave Martin
2017-09-19 17:13 ` Catalin Marinas
2017-09-19 17:13 ` Catalin Marinas
2017-08-31 17:00 ` [PATCH v2 12/28] arm64/sve: Support vector length resetting for new processes Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 8:47 ` Alex Bennée
2017-09-14 8:47 ` Alex Bennée
2017-09-14 8:47 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 13/28] arm64/sve: Signal handling support Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 9:30 ` Alex Bennée
2017-09-14 9:30 ` Alex Bennée
2017-09-14 9:30 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 14/28] arm64/sve: Backend logic for setting the vector length Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-13 17:29 ` Catalin Marinas
2017-09-13 17:29 ` Catalin Marinas
2017-09-13 19:06 ` Dave Martin
2017-09-13 19:06 ` Dave Martin
2017-09-13 22:11 ` Catalin Marinas
2017-09-13 22:11 ` Catalin Marinas
2017-10-05 16:42 ` Dave Martin
2017-10-05 16:42 ` Dave Martin
2017-10-05 16:53 ` Catalin Marinas
2017-10-05 16:53 ` Catalin Marinas
2017-10-05 17:04 ` Dave Martin
2017-10-05 17:04 ` Dave Martin
2017-09-20 10:57 ` Alan Hayward
2017-09-20 10:57 ` Alan Hayward
2017-09-20 10:59 ` Alan Hayward
2017-09-20 10:59 ` Alan Hayward
2017-09-20 11:09 ` Dave Martin
2017-09-20 11:09 ` Dave Martin
2017-09-20 18:08 ` Alan Hayward
2017-09-20 18:08 ` Alan Hayward
2017-09-21 11:19 ` Dave Martin
2017-09-21 11:19 ` Dave Martin
2017-09-21 11:57 ` Alan Hayward
2017-09-21 11:57 ` Alan Hayward
2017-08-31 17:00 ` [PATCH v2 15/28] arm64: cpufeature: Move sys_caps_initialised declarations Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 9:33 ` Alex Bennée
2017-09-14 9:33 ` Alex Bennée
2017-09-14 9:33 ` Alex Bennée
2017-09-14 9:35 ` Suzuki K Poulose
2017-09-14 9:35 ` Suzuki K Poulose
2017-08-31 17:00 ` [PATCH v2 16/28] arm64/sve: Probe SVE capabilities and usable vector lengths Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 9:45 ` Alex Bennée
2017-09-14 9:45 ` Alex Bennée
2017-09-14 9:45 ` Alex Bennée
2017-09-28 14:22 ` Dave Martin
2017-09-28 14:22 ` Dave Martin
2017-09-28 17:32 ` Alex Bennée
2017-09-28 17:32 ` Alex Bennée
2017-09-28 17:32 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 17/28] arm64/sve: Preserve SVE registers around kernel-mode NEON use Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 10:52 ` Alex Bennée
2017-09-14 10:52 ` Alex Bennée
2017-09-14 10:52 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 18/28] arm64/sve: Preserve SVE registers around EFI runtime service calls Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 11:01 ` Alex Bennée
2017-09-14 11:01 ` Alex Bennée
2017-09-14 11:01 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 19/28] arm64/sve: ptrace and ELF coredump support Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-06 16:21 ` Okamoto, Takayuki
2017-09-06 16:21 ` Okamoto, Takayuki
2017-09-06 18:16 ` Dave Martin
2017-09-06 18:16 ` Dave Martin
2017-09-07 5:11 ` Okamoto, Takayuki
2017-09-07 5:11 ` Okamoto, Takayuki
2017-09-07 5:11 ` Okamoto, Takayuki
2017-09-08 13:11 ` Dave Martin
2017-09-08 13:11 ` Dave Martin
2017-09-14 12:57 ` Alex Bennée
2017-09-14 12:57 ` Alex Bennée
2017-09-14 12:57 ` Alex Bennée
2017-09-28 14:57 ` Dave Martin
2017-09-28 14:57 ` Dave Martin
2017-09-29 12:46 ` Dave Martin
2017-09-29 12:46 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 20/28] arm64/sve: Add prctl controls for userspace vector length management Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 13:02 ` Alex Bennée
2017-09-14 13:02 ` Alex Bennée
2017-09-14 13:02 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 21/28] arm64/sve: Add sysctl to set the default vector length for new processes Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 13:05 ` Alex Bennée
2017-09-14 13:05 ` Alex Bennée
2017-09-14 13:05 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 22/28] arm64/sve: KVM: Prevent guests from using SVE Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 13:28 ` Alex Bennée
2017-09-14 13:28 ` Alex Bennée
2017-09-14 13:28 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 23/28] arm64/sve: KVM: Treat guest SVE use as undefined instruction execution Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 13:30 ` Alex Bennée
2017-09-14 13:30 ` Alex Bennée
2017-09-14 13:30 ` Alex Bennée
2017-09-14 13:31 ` Alex Bennée
2017-09-14 13:31 ` Alex Bennée
2017-09-14 13:31 ` Alex Bennée
2017-09-29 13:00 ` Dave Martin
2017-09-29 13:00 ` Dave Martin
2017-09-29 14:43 ` Alex Bennée
2017-09-29 14:43 ` Alex Bennée
2017-09-29 14:43 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 24/28] arm64/sve: KVM: Hide SVE from CPU features exposed to guests Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-09-14 13:32 ` Alex Bennée
2017-09-14 13:32 ` Alex Bennée
2017-09-14 13:32 ` Alex Bennée
2017-08-31 17:00 ` [PATCH v2 25/28] arm64/sve: Detect SVE and activate runtime support Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-08-31 17:00 ` [PATCH v2 26/28] arm64/sve: Add documentation Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-10-05 16:39 ` Szabolcs Nagy
2017-10-05 16:39 ` Szabolcs Nagy
2017-10-05 17:02 ` Dave Martin
2017-10-05 17:02 ` Dave Martin
2017-10-06 15:43 ` Szabolcs Nagy
2017-10-06 15:43 ` Szabolcs Nagy
2017-10-06 17:37 ` Dave Martin
2017-10-06 17:37 ` Dave Martin
2017-10-09 9:34 ` Alex Bennée
2017-10-09 9:34 ` Alex Bennée
2017-10-09 9:34 ` Alex Bennée
2017-10-09 9:49 ` Dave Martin
2017-10-09 9:49 ` Dave Martin
2017-10-09 14:07 ` Alex Bennée
2017-10-09 14:07 ` Alex Bennée
2017-10-09 14:07 ` Alex Bennée
2017-10-09 16:20 ` Dave Martin
2017-10-09 16:20 ` Dave Martin
2017-08-31 17:00 ` [RFC PATCH v2 27/28] arm64: signal: Report signal frame size to userspace via auxv Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-08-31 17:00 ` Dave Martin
2017-08-31 17:01 ` [RFC PATCH v2 28/28] arm64/sve: signal: Include SVE when computing AT_MINSIGSTKSZ Dave Martin
2017-08-31 17:01 ` Dave Martin
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