From: Vladimir Murzin <vladimir.murzin@arm.com> To: Christoffer Dall <christoffer.dall@linaro.org> Cc: marc.zyngier@arm.com, andre.przywara@arm.com, kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 7/7] ARM: KVM: Unlock vgic-v3 support Date: Wed, 7 Sep 2016 11:48:52 +0100 [thread overview] Message-ID: <57CFF094.5000704@arm.com> (raw) In-Reply-To: <20160906165527.GG23592@cbox> On 06/09/16 17:55, Christoffer Dall wrote: > On Tue, Sep 06, 2016 at 02:23:16PM +0100, Vladimir Murzin wrote: >> >> Sorry, missed this one >> >> On 05/09/16 12:29, Christoffer Dall wrote: >>>> >>>>> +static bool __hyp_text __has_useable_gicv3_cpuif(void) >>>>> +{ >>>>> + if (IS_ENABLED(CONFIG_ARM_GIC_V3) && (read_sysreg(ID_PFR1) >> 28)) >>> Do we have a define for bit 28 we could use? >> >> I'll check it. >> >>> >>> Does this actually work on all v7 boards? The v7 ARM ARM seems to state >>> that this bitfield is Reserved, UNK. Does that somehow mean 'is going >>> to be zero'? >> >> It is how v7ARM ARM I have defines UNK >> >> An abbreviation indicating that software must treat a field as >> containing an UNKNOWN value. Hardware must implement the bit as read as >> 0, or all 0s for a bit field. Software must not rely on the field >> reading as zero. >> >> It seems goes under 'is going to be zero' case, no? >> > The last sentence is disturbing to me, and feels slightly contradicting > itself. Reading the UNKNOWN description doesn't help much either. > > Perhaps you can ask around internally and figure out what the precise > answer to this is? Since it is kind of implementation dependant thing the precise answer from here hardly help, IMO. We still have non-zero chance to see something scary. OTOH, why do we care of all v7 boards if none of them have CONFIG_ARM_GIC_V3 defined? Cheers Vladimir > > Thanks, > -Christoffer > >
WARNING: multiple messages have this Message-ID (diff)
From: vladimir.murzin@arm.com (Vladimir Murzin) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v2 7/7] ARM: KVM: Unlock vgic-v3 support Date: Wed, 7 Sep 2016 11:48:52 +0100 [thread overview] Message-ID: <57CFF094.5000704@arm.com> (raw) In-Reply-To: <20160906165527.GG23592@cbox> On 06/09/16 17:55, Christoffer Dall wrote: > On Tue, Sep 06, 2016 at 02:23:16PM +0100, Vladimir Murzin wrote: >> >> Sorry, missed this one >> >> On 05/09/16 12:29, Christoffer Dall wrote: >>>> >>>>> +static bool __hyp_text __has_useable_gicv3_cpuif(void) >>>>> +{ >>>>> + if (IS_ENABLED(CONFIG_ARM_GIC_V3) && (read_sysreg(ID_PFR1) >> 28)) >>> Do we have a define for bit 28 we could use? >> >> I'll check it. >> >>> >>> Does this actually work on all v7 boards? The v7 ARM ARM seems to state >>> that this bitfield is Reserved, UNK. Does that somehow mean 'is going >>> to be zero'? >> >> It is how v7ARM ARM I have defines UNK >> >> An abbreviation indicating that software must treat a field as >> containing an UNKNOWN value. Hardware must implement the bit as read as >> 0, or all 0s for a bit field. Software must not rely on the field >> reading as zero. >> >> It seems goes under 'is going to be zero' case, no? >> > The last sentence is disturbing to me, and feels slightly contradicting > itself. Reading the UNKNOWN description doesn't help much either. > > Perhaps you can ask around internally and figure out what the precise > answer to this is? Since it is kind of implementation dependant thing the precise answer from here hardly help, IMO. We still have non-zero chance to see something scary. OTOH, why do we care of all v7 boards if none of them have CONFIG_ARM_GIC_V3 defined? Cheers Vladimir > > Thanks, > -Christoffer > >
next prev parent reply other threads:[~2016-09-07 10:40 UTC|newest] Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-08-16 10:46 [PATCH v2 0/7] ARM: KVM: Support for vgic-v3 Vladimir Murzin 2016-08-16 10:46 ` Vladimir Murzin 2016-08-16 10:46 ` [PATCH v2 1/7] arm64: KVM: Move GIC accessors to arch_gicv3.h Vladimir Murzin 2016-08-16 10:46 ` Vladimir Murzin 2016-09-05 11:28 ` Christoffer Dall 2016-09-05 11:28 ` Christoffer Dall 2016-09-06 12:33 ` Vladimir Murzin 2016-09-06 12:33 ` Vladimir Murzin 2016-08-16 10:46 ` [PATCH v2 2/7] arm64: KVM: Move vgic-v3 save/restore to virt/kvm/arm/hyp Vladimir Murzin 2016-08-16 10:46 ` Vladimir Murzin 2016-08-16 10:46 ` [PATCH v2 3/7] KVM: arm: vgic-new: improve compatibility with 32-bit Vladimir Murzin 2016-08-16 10:46 ` Vladimir Murzin 2016-09-05 11:29 ` Christoffer Dall 2016-09-05 11:29 ` Christoffer Dall 2016-09-06 12:41 ` Vladimir Murzin 2016-09-06 12:41 ` Vladimir Murzin 2016-09-06 13:22 ` Christoffer Dall 2016-09-06 13:22 ` Christoffer Dall 2016-09-06 13:54 ` Vladimir Murzin 2016-09-06 13:54 ` Vladimir Murzin 2016-09-06 16:31 ` Christoffer Dall 2016-09-06 16:31 ` Christoffer Dall 2016-09-07 9:06 ` Vladimir Murzin 2016-09-07 9:06 ` Vladimir Murzin 2016-09-07 9:43 ` Christoffer Dall 2016-09-07 9:43 ` Christoffer Dall 2016-08-16 10:46 ` [PATCH v2 4/7] ARM: update MPIDR accessors macro Vladimir Murzin 2016-08-16 10:46 ` Vladimir Murzin 2016-09-05 11:29 ` Christoffer Dall 2016-09-05 11:29 ` Christoffer Dall 2016-09-06 12:42 ` Vladimir Murzin 2016-09-06 12:42 ` Vladimir Murzin 2016-08-16 10:46 ` [PATCH v2 5/7] ARM: move system register accessors to asm/cp15.h Vladimir Murzin 2016-08-16 10:46 ` Vladimir Murzin 2016-09-05 11:29 ` Christoffer Dall 2016-09-05 11:29 ` Christoffer Dall 2016-09-06 13:05 ` Vladimir Murzin 2016-09-06 13:05 ` Vladimir Murzin 2016-09-06 16:34 ` Christoffer Dall 2016-09-06 16:34 ` Christoffer Dall 2016-08-16 10:46 ` [PATCH v2 6/7] ARM: KVM: Get ready to use vgic-v3 Vladimir Murzin 2016-08-16 10:46 ` Vladimir Murzin 2016-09-05 11:29 ` Christoffer Dall 2016-09-05 11:29 ` Christoffer Dall 2016-09-06 13:12 ` Vladimir Murzin 2016-09-06 13:12 ` Vladimir Murzin 2016-09-06 16:49 ` Christoffer Dall 2016-09-06 16:49 ` Christoffer Dall 2016-08-16 10:46 ` [PATCH v2 7/7] ARM: KVM: Unlock vgic-v3 support Vladimir Murzin 2016-08-16 10:46 ` Vladimir Murzin 2016-09-05 11:29 ` Christoffer Dall 2016-09-05 11:29 ` Christoffer Dall 2016-09-06 13:08 ` Marc Zyngier 2016-09-06 13:08 ` Marc Zyngier 2016-09-06 13:18 ` Vladimir Murzin 2016-09-06 13:18 ` Vladimir Murzin 2016-09-06 16:52 ` Christoffer Dall 2016-09-06 16:52 ` Christoffer Dall 2016-09-06 13:23 ` Vladimir Murzin 2016-09-06 13:23 ` Vladimir Murzin 2016-09-06 16:55 ` Christoffer Dall 2016-09-06 16:55 ` Christoffer Dall 2016-09-07 10:48 ` Vladimir Murzin [this message] 2016-09-07 10:48 ` Vladimir Murzin 2016-09-07 12:58 ` Christoffer Dall 2016-09-07 12:58 ` Christoffer Dall 2016-09-07 14:20 ` Peter Maydell 2016-09-07 14:20 ` Peter Maydell 2016-09-07 14:47 ` Christoffer Dall 2016-09-07 14:47 ` Christoffer Dall 2016-09-05 11:28 ` [PATCH v2 0/7] ARM: KVM: Support for vgic-v3 Christoffer Dall 2016-09-05 11:28 ` Christoffer Dall 2016-09-06 12:32 ` Vladimir Murzin 2016-09-06 12:32 ` Vladimir Murzin
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