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Tue, 27 Jul 2021 18:17:20 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m8RXF-00FkFf-JK for linux-arm-kernel@lists.infradead.org; Tue, 27 Jul 2021 18:10:35 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1A0B060F4F; Tue, 27 Jul 2021 18:10:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627409433; bh=eAQ6Y5NFEbqzK+Qxa6eEtOaPVZxtmmYG8Cp8wn4awk0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ZUdLTBGArL4F4dnHexEQOVZW0mHKBsiDWS3JVNmUjI74QPdj4B6Ri+jpbUV/xu6vi eR6EWfI50nJjGQ/Ud9qNfpzAu7g5qbFLSRBRr9LLgHzuiDlwmyBpqwt1rksx5FXj+W RjKFbP2JQp0zt2oawjyukgEhkFC/vYhsgmCrBT3mOYBm8yz2k/zHY5fu0Lw8eMA6dD wF3F28tyugzeNkNeGJ3McDWo3mCY7B/yGl/Vawcltq99rALZWYg5zEeeydatefT0q2 kA0irLtyHyn9i0FTjNibDfHiuOyP/Jund7o+A26RksFueTTT9tcVaYWmuBPYjuV6j3 xcNbI/axou1ew== Date: Tue, 27 Jul 2021 19:10:27 +0100 From: Will Deacon To: Marc Zyngier Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, qperret@google.com, dbrazdil@google.com, Srivatsa Vaddagiri , Shanker R Donthineni , James Morse , Suzuki K Poulose , Alexandru Elisei , kernel-team@android.com Subject: Re: [PATCH 01/16] KVM: arm64: Generalise VM features into a set of flags Message-ID: <20210727181026.GA19173@willie-the-truck> References: <20210715163159.1480168-1-maz@kernel.org> <20210715163159.1480168-2-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210715163159.1480168-2-maz@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210727_111033_695898_C06F96ED X-CRM114-Status: GOOD ( 21.36 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jul 15, 2021 at 05:31:44PM +0100, Marc Zyngier wrote: > We currently deal with a set of booleans for VM features, > while they could be better represented as set of flags > contained in an unsigned long, similarily to what we are > doing on the CPU side. > > Signed-off-by: Marc Zyngier > --- > arch/arm64/include/asm/kvm_host.h | 12 +++++++----- > arch/arm64/kvm/arm.c | 5 +++-- > arch/arm64/kvm/mmio.c | 3 ++- > 3 files changed, 12 insertions(+), 8 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 41911585ae0c..4add6c27251f 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -122,7 +122,10 @@ struct kvm_arch { > * should) opt in to this feature if KVM_CAP_ARM_NISV_TO_USER is > * supported. > */ > - bool return_nisv_io_abort_to_user; > +#define KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER 0 > + /* Memory Tagging Extension enabled for the guest */ > +#define KVM_ARCH_FLAG_MTE_ENABLED 1 > + unsigned long flags; One downside of packing all these together is that updating 'flags' now requires an atomic rmw sequence (i.e. set_bit()). Then again, that's probably for the best anyway given that kvm_vm_ioctl_enable_cap() looks like it doesn't hold any locks. > /* > * VM-wide PMU filter, implemented as a bitmap and big enough for > @@ -133,9 +136,6 @@ struct kvm_arch { > > u8 pfr0_csv2; > u8 pfr0_csv3; > - > - /* Memory Tagging Extension enabled for the guest */ > - bool mte_enabled; > }; > > struct kvm_vcpu_fault_info { > @@ -777,7 +777,9 @@ bool kvm_arm_vcpu_is_finalized(struct kvm_vcpu *vcpu); > #define kvm_arm_vcpu_sve_finalized(vcpu) \ > ((vcpu)->arch.flags & KVM_ARM64_VCPU_SVE_FINALIZED) > > -#define kvm_has_mte(kvm) (system_supports_mte() && (kvm)->arch.mte_enabled) > +#define kvm_has_mte(kvm) \ > + (system_supports_mte() && \ > + test_bit(KVM_ARCH_FLAG_MTE_ENABLED, &(kvm)->arch.flags)) Not an issue with this patch, but I just noticed that the system_supports_mte() check is redundant here as we only allow the flag to be set if that's already the case. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel