From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Martin Subject: Re: [PATCH 09/14] KVM: arm64/sve: Simplify KVM_REG_ARM64_SVE_VLS array sizing Date: Tue, 16 Apr 2019 13:41:42 +0100 Message-ID: <20190416124142.GO3567@e103592.cambridge.arm.com> References: <1555086498-26691-1-git-send-email-Dave.Martin@arm.com> <1555086498-26691-10-git-send-email-Dave.Martin@arm.com> <20190415152037.d4ewqbxw7fbbbo3b@kamzik.brq.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 238E04A506 for ; Tue, 16 Apr 2019 08:41:49 -0400 (EDT) Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id tRYlvWKdC+GC for ; Tue, 16 Apr 2019 08:41:47 -0400 (EDT) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id A4B3E4A4FF for ; Tue, 16 Apr 2019 08:41:47 -0400 (EDT) Content-Disposition: inline In-Reply-To: <20190415152037.d4ewqbxw7fbbbo3b@kamzik.brq.redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu To: Andrew Jones Cc: Okamoto Takayuki , Christoffer Dall , Ard Biesheuvel , Marc Zyngier , Catalin Marinas , Will Deacon , Zhang Lei , Julien Grall , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org List-Id: kvmarm@lists.cs.columbia.edu On Mon, Apr 15, 2019 at 05:20:37PM +0200, Andrew Jones wrote: > On Fri, Apr 12, 2019 at 05:28:13PM +0100, Dave Martin wrote: > > A complicated DIV_ROUND_UP() expression is currently written out > > explicitly in multiple places in order to specify the size of the > > bitmap exchanged with userspace to represent the value of the > > KVM_REG_ARM64_SVE_VLS pseudo-register. > > > > To make this more readable, this patch replaces these with a single > > define. > > > > Since the number of words in a bitmap is just the index of the last > > word used + 1, this patch expresses the bound that way instead. > > This should make it clearer what is being expressed. > > > > Since use of DIV_ROUND_UP() was the only reason for including > > in guest.c, this patch removes that #include. > > > > No functional change. > > > > Suggested-by: Andrew Jones > > Signed-off-by: Dave Martin > > --- > > arch/arm64/kvm/guest.c | 9 +++++---- > > 1 file changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c > > index 73044e3..f025a2f 100644 > > --- a/arch/arm64/kvm/guest.c > > +++ b/arch/arm64/kvm/guest.c > > @@ -23,7 +23,6 @@ > > #include > > #include > > #include > > -#include > > #include > > #include > > #include > > @@ -209,8 +208,10 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) > > #define vq_word(vq) (((vq) - SVE_VQ_MIN) / 64) > > #define vq_mask(vq) ((u64)1 << ((vq) - SVE_VQ_MIN) % 64) > > > > +#define SVE_VLS_WORDS (vq_word(SVE_VQ_MAX) + 1) > > + > > static bool vq_present( > > - const u64 (*const vqs)[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)], > > + const u64 (*const vqs)[SVE_VLS_WORDS], > > unsigned int vq) > > { > > return (*vqs)[vq_word(vq)] & vq_mask(vq); > > @@ -219,7 +220,7 @@ static bool vq_present( > > static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) > > { > > unsigned int max_vq, vq; > > - u64 vqs[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)]; > > + u64 vqs[SVE_VLS_WORDS]; > > > > if (!vcpu_has_sve(vcpu)) > > return -ENOENT; > > @@ -243,7 +244,7 @@ static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) > > static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) > > { > > unsigned int max_vq, vq; > > - u64 vqs[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)]; > > + u64 vqs[SVE_VLS_WORDS]; > > > > if (!vcpu_has_sve(vcpu)) > > return -ENOENT; > > -- > > 2.1.4 > > > > This is good, but I wonder if we could define the number of VLS words in > the documentation in terms of SVE_VQ_MAX too. Currently it's just the > hard coded 8 ("__u64 vector_lengths[8]"). > > Reviewed-by: Andrew Jones I see your point, but SVE_VQ_MAX isn't really part of the KVM API, so I was avoiding it here. [8] is at least impossible to misinterpret, even if it's not the most self-explanatory option. Is that OK? Cheers ---Dave From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C64DC10F13 for ; Tue, 16 Apr 2019 12:41:52 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 8B71B206BA for ; Tue, 16 Apr 2019 12:41:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8B71B206BA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 0F4374A51D; Tue, 16 Apr 2019 08:41:51 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id EO8uAyu265tz; Tue, 16 Apr 2019 08:41:49 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id BCBEF4A511; Tue, 16 Apr 2019 08:41:49 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 238E04A506 for ; Tue, 16 Apr 2019 08:41:49 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id tRYlvWKdC+GC for ; Tue, 16 Apr 2019 08:41:47 -0400 (EDT) Received: from foss.arm.com (usa-sjc-mx-foss1.foss.arm.com [217.140.101.70]) by mm01.cs.columbia.edu (Postfix) with ESMTP id A4B3E4A4FF for ; Tue, 16 Apr 2019 08:41:47 -0400 (EDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 05D38EBD; Tue, 16 Apr 2019 05:41:47 -0700 (PDT) Received: from e103592.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 12D553F706; Tue, 16 Apr 2019 05:41:44 -0700 (PDT) Date: Tue, 16 Apr 2019 13:41:42 +0100 From: Dave Martin To: Andrew Jones Subject: Re: [PATCH 09/14] KVM: arm64/sve: Simplify KVM_REG_ARM64_SVE_VLS array sizing Message-ID: <20190416124142.GO3567@e103592.cambridge.arm.com> References: <1555086498-26691-1-git-send-email-Dave.Martin@arm.com> <1555086498-26691-10-git-send-email-Dave.Martin@arm.com> <20190415152037.d4ewqbxw7fbbbo3b@kamzik.brq.redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190415152037.d4ewqbxw7fbbbo3b@kamzik.brq.redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Cc: Okamoto Takayuki , Christoffer Dall , Ard Biesheuvel , Marc Zyngier , Catalin Marinas , Will Deacon , Zhang Lei , Julien Grall , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu Message-ID: <20190416124142.qaPxnnF5uyUBNrJpt8EL2YMDfsWLB7pkt5thh_98XZs@z> On Mon, Apr 15, 2019 at 05:20:37PM +0200, Andrew Jones wrote: > On Fri, Apr 12, 2019 at 05:28:13PM +0100, Dave Martin wrote: > > A complicated DIV_ROUND_UP() expression is currently written out > > explicitly in multiple places in order to specify the size of the > > bitmap exchanged with userspace to represent the value of the > > KVM_REG_ARM64_SVE_VLS pseudo-register. > > > > To make this more readable, this patch replaces these with a single > > define. > > > > Since the number of words in a bitmap is just the index of the last > > word used + 1, this patch expresses the bound that way instead. > > This should make it clearer what is being expressed. > > > > Since use of DIV_ROUND_UP() was the only reason for including > > in guest.c, this patch removes that #include. > > > > No functional change. > > > > Suggested-by: Andrew Jones > > Signed-off-by: Dave Martin > > --- > > arch/arm64/kvm/guest.c | 9 +++++---- > > 1 file changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c > > index 73044e3..f025a2f 100644 > > --- a/arch/arm64/kvm/guest.c > > +++ b/arch/arm64/kvm/guest.c > > @@ -23,7 +23,6 @@ > > #include > > #include > > #include > > -#include > > #include > > #include > > #include > > @@ -209,8 +208,10 @@ static int set_core_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) > > #define vq_word(vq) (((vq) - SVE_VQ_MIN) / 64) > > #define vq_mask(vq) ((u64)1 << ((vq) - SVE_VQ_MIN) % 64) > > > > +#define SVE_VLS_WORDS (vq_word(SVE_VQ_MAX) + 1) > > + > > static bool vq_present( > > - const u64 (*const vqs)[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)], > > + const u64 (*const vqs)[SVE_VLS_WORDS], > > unsigned int vq) > > { > > return (*vqs)[vq_word(vq)] & vq_mask(vq); > > @@ -219,7 +220,7 @@ static bool vq_present( > > static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) > > { > > unsigned int max_vq, vq; > > - u64 vqs[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)]; > > + u64 vqs[SVE_VLS_WORDS]; > > > > if (!vcpu_has_sve(vcpu)) > > return -ENOENT; > > @@ -243,7 +244,7 @@ static int get_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) > > static int set_sve_vls(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg) > > { > > unsigned int max_vq, vq; > > - u64 vqs[DIV_ROUND_UP(SVE_VQ_MAX - SVE_VQ_MIN + 1, 64)]; > > + u64 vqs[SVE_VLS_WORDS]; > > > > if (!vcpu_has_sve(vcpu)) > > return -ENOENT; > > -- > > 2.1.4 > > > > This is good, but I wonder if we could define the number of VLS words in > the documentation in terms of SVE_VQ_MAX too. Currently it's just the > hard coded 8 ("__u64 vector_lengths[8]"). > > Reviewed-by: Andrew Jones I see your point, but SVE_VQ_MAX isn't really part of the KVM API, so I was avoiding it here. [8] is at least impossible to misinterpret, even if it's not the most self-explanatory option. Is that OK? Cheers ---Dave _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm