From mboxrd@z Thu Jan 1 00:00:00 1970 From: pbonzini@redhat.com (Paolo Bonzini) Date: Wed, 04 Mar 2015 18:03:11 +0100 Subject: [RFC/RFT PATCH 0/3] arm64: KVM: work around incoherency with uncached guest mappings In-Reply-To: <20150304142943.GU28951@e104818-lin.cambridge.arm.com> References: <20150220153626.GB10942@hawk.usersys.redhat.com> <20150224145529.GA5498@hawk.usersys.redhat.com> <20150302163146.GB9686@lvm> <54F51A63.4060302@samsung.com> <20150304113505.GS28951@e104818-lin.cambridge.arm.com> <20150304122956.GT28951@e104818-lin.cambridge.arm.com> <20150304141212.GA5352@hawk.usersys.redhat.com> <20150304142943.GU28951@e104818-lin.cambridge.arm.com> Message-ID: <54F73ACF.1090605@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 04/03/2015 15:29, Catalin Marinas wrote: > I disagree it is 100% a host-side issue. It is a host-side issue _if_ > the host tells the guest that the (virtual) device is non-coherent (or, > more precisely, it does not explicitly tell the guest that the device is > coherent). If the guest thinks the (virtual) device is non-coherent > because of information passed by the host, I fully agree that the host > needs to manage the cache coherency. > > However, the host could also pass a "dma-coherent" property in the DT > given to the guest and avoid any form of cache maintenance. If the guest > does not honour such coherency property, it's a guest problem and it > needs fixing in the guest. This isn't any different from a real physical > device behaviour. Can you add that property to the device tree for PCI devices too? Paolo