From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C636A315AF; Wed, 6 Dec 2023 11:39:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JG5xMnLV" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 41B43C433C9; Wed, 6 Dec 2023 11:39:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1701862746; bh=VACpM7Rme6S0irInDKWgO8xLCrPsqk274n5MkiWmcsw=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=JG5xMnLV5Sd+LjMbCFz5yXzqsLubGU2gW7YaIunlRH/fySYpyxfDxa4lZpjMcjveL lZ6d4XPF4vvtPie7R0QCZlbF5t7ZQslO2toupZKR4nEwTzwEb79AR+eInyZiUh/hKu 66NFewRMMsnzSXyIZYomW2tGpjJsuP4V4k3QyoHFSw2gkX9szLSP26C+qZ2t6XX+5t ALJMhmdcZLXgeNSn/snBfLrt1Ni3K3qJXpRyK44cXrI67dE8bkwv8PkEUD552kUDUt yw7rc7ZIr4DmbDAeXtQ+2hzYvgJ3uh9VrSgy80P39hgCEcY11xUJ1uTWgU2r/2I4Br vBqudpbAgwXTw== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1rAqF5-001rsK-Ld; Wed, 06 Dec 2023 11:39:03 +0000 Date: Wed, 06 Dec 2023 11:39:03 +0000 Message-ID: <868r67blwo.wl-maz@kernel.org> From: Marc Zyngier To: Catalin Marinas Cc: Jason Gunthorpe , ankita@nvidia.com, Shameerali Kolothum Thodi , oliver.upton@linux.dev, suzuki.poulose@arm.com, yuzenghui@huawei.com, will@kernel.org, ardb@kernel.org, akpm@linux-foundation.org, gshan@redhat.com, aniketa@nvidia.com, cjia@nvidia.com, kwankhede@nvidia.com, targupta@nvidia.com, vsethi@nvidia.com, acurrid@nvidia.com, apopple@nvidia.com, jhubbard@nvidia.com, danw@nvidia.com, mochs@nvidia.com, kvmarm@lists.linux.dev, kvm@vger.kernel.org, lpieralisi@kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 1/1] KVM: arm64: allow the VM to select DEVICE_* and NORMAL_NC for IO memory In-Reply-To: References: <20231205033015.10044-1-ankita@nvidia.com> <86fs0hatt3.wl-maz@kernel.org> <20231205130517.GD2692119@nvidia.com> <20231205164318.GG2692119@nvidia.com> <86bkb4bn2v.wl-maz@kernel.org> <86a5qobkt8.wl-maz@kernel.org> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/29.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: catalin.marinas@arm.com, jgg@nvidia.com, ankita@nvidia.com, shameerali.kolothum.thodi@huawei.com, oliver.upton@linux.dev, suzuki.poulose@arm.com, yuzenghui@huawei.com, will@kernel.org, ardb@kernel.org, akpm@linux-foundation.org, gshan@redhat.com, aniketa@nvidia.com, cjia@nvidia.com, kwankhede@nvidia.com, targupta@nvidia.com, vsethi@nvidia.com, acurrid@nvidia.com, apopple@nvidia.com, jhubbard@nvidia.com, danw@nvidia.com, mochs@nvidia.com, kvmarm@lists.linux.dev, kvm@vger.kernel.org, lpieralisi@kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Tue, 05 Dec 2023 18:40:42 +0000, Catalin Marinas wrote: > > On Tue, Dec 05, 2023 at 05:50:27PM +0000, Marc Zyngier wrote: > > On Tue, 05 Dec 2023 17:33:01 +0000, > > Catalin Marinas wrote: > > > Ideally we should do this for vfio only but we don't have an easy > > > way to convey this to KVM. > > > > But if we want to limit this to PCIe, we'll have to find out. The > > initial proposal (a long while ago) had a flag conveying some > > information, and I'd definitely feel more confident having something > > like that. > > We can add a VM_PCI_IO in the high vma flags to be set by > vfio_pci_core_mmap(), though it limits it to 64-bit architectures. KVM > knows this is PCI and relaxes things a bit. It's not generic though if > we need this later for something else. Either that, or something actually describing the attributes that VFIO wants. And I very much want it to be a buy-in behaviour, not something that automagically happens and changes the default behaviour for everyone based on some hand-wavy assertions. If that means a userspace change, fine by me. The VMM better know what is happening. M. -- Without deviation from the norm, progress is not possible.