From mboxrd@z Thu Jan 1 00:00:00 1970 From: Auger Eric Subject: Re: [RFC 07/13] KVM: arm64: ITS: Change entry_size and indirect bit in BASER Date: Fri, 13 Jan 2017 09:57:27 +0100 Message-ID: <89752a29-d533-1f4c-9e9b-93e8bd0556b3@redhat.com> References: <1484236613-24633-1-git-send-email-eric.auger@redhat.com> <1484236613-24633-8-git-send-email-eric.auger@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: andre.przywara@arm.com, Prasun.Kapoor@cavium.com, dgilbert@redhat.com, pbonzini@redhat.com To: Marc Zyngier , eric.auger.pro@gmail.com, christoffer.dall@linaro.org, vijayak@caviumnetworks.com, Vijaya.Kumar@cavium.com, peter.maydell@linaro.org, linux-arm-kernel@lists.infradead.org, drjones@redhat.com, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org Return-path: In-Reply-To: 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 List-Id: kvm.vger.kernel.org Hi Marc, On 12/01/2017 18:05, Marc Zyngier wrote: > On 12/01/17 15:56, Eric Auger wrote: >> Change the device table entry_size to 16 bytes instead of 8. >> We also Store the device and collection device in the its >> struct. >> >> The patch also clears the indirect bit for the device BASER. >> The indirect bit is set as read-only. > > Err... Why? We *really* want to continue supporting indirect tables, as > this is a massive memory saver for the guest. > >> >> Signed-off-by: Eric Auger >> >> --- >> >> TODO: investigate support of 2 level tables, ie. enabling >> Indirect = 1. Support of 2 level tables is implementation >> defined. > > Clearly, that's a regression. What exactly is the issue that decided you > to disable it? Well no valuable reason besides I saw it was optional, lack of time/knowledge and a bit of laziness. I will address this requirement in my next respin. For my curiosity why did we choose not allowing the feature for collections. Is that just because we think their number if going sufficiently small compared to devices? Thanks Eric > > Thanks, > > M. > From mboxrd@z Thu Jan 1 00:00:00 1970 From: eric.auger@redhat.com (Auger Eric) Date: Fri, 13 Jan 2017 09:57:27 +0100 Subject: [RFC 07/13] KVM: arm64: ITS: Change entry_size and indirect bit in BASER In-Reply-To: References: <1484236613-24633-1-git-send-email-eric.auger@redhat.com> <1484236613-24633-8-git-send-email-eric.auger@redhat.com> Message-ID: <89752a29-d533-1f4c-9e9b-93e8bd0556b3@redhat.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Marc, On 12/01/2017 18:05, Marc Zyngier wrote: > On 12/01/17 15:56, Eric Auger wrote: >> Change the device table entry_size to 16 bytes instead of 8. >> We also Store the device and collection device in the its >> struct. >> >> The patch also clears the indirect bit for the device BASER. >> The indirect bit is set as read-only. > > Err... Why? We *really* want to continue supporting indirect tables, as > this is a massive memory saver for the guest. > >> >> Signed-off-by: Eric Auger >> >> --- >> >> TODO: investigate support of 2 level tables, ie. enabling >> Indirect = 1. Support of 2 level tables is implementation >> defined. > > Clearly, that's a regression. What exactly is the issue that decided you > to disable it? Well no valuable reason besides I saw it was optional, lack of time/knowledge and a bit of laziness. I will address this requirement in my next respin. For my curiosity why did we choose not allowing the feature for collections. Is that just because we think their number if going sufficiently small compared to devices? Thanks Eric > > Thanks, > > M. >