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([2001:b07:6468:f312:c8dd:75d4:99ab:290a]) by smtp.googlemail.com with ESMTPSA id bp5-20020a170907918500b006f022c102a4sm602143ejb.124.2022.04.22.03.19.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Apr 2022 03:19:52 -0700 (PDT) Message-ID: <36978590-c714-d0ba-6e4e-ab0016136381@redhat.com> Date: Fri, 22 Apr 2022 12:19:51 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.0 Content-Language: en-US To: Marc Zyngier Cc: Oliver Upton , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, will@kernel.org, apatel@ventanamicro.com, atishp@rivosinc.com, seanjc@google.com, pgonda@google.com References: <20220421180443.1465634-1-pbonzini@redhat.com> <87a6cda13p.wl-maz@kernel.org> From: Paolo Bonzini Subject: Re: [PATCH 0/4] KVM: fix KVM_EXIT_SYSTEM_EVENT mess In-Reply-To: <87a6cda13p.wl-maz@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/22/22 12:01, Marc Zyngier wrote: >> These patches are against kvm/next, so that is already what I did. :) > > Can you please post a complete series? It is becoming really hard to > track what you are doing. Yes, I'll post a complete series for kvm/master in a second. >> On the other hand right now the ARM and RISC-V flags are unusable with >> 32-bit userspace, so we need to fix _something_ in 5.18 as well. > > What 32bit userspace? arm64 doesn't have any that can interact with KVM, > so I don't see anything to fix on that front. You're right, ARM64 does not define KVM_COMPAT. But RISC-V does. >> For your proposal, all that's missing is a 5.18 patch to add the >> padding. But since the flags UAPI was completely unused before 5.18 >> and there's no reason to inflict the different naming of fields to >> userspace. So I think we want to apply this UAPI change in 5.18 too. > > As it was pointed out already, CrosVM has already started looking at > the flags. The fact that it was always 0 until now doesn't make it > less of a UAPI. I heard that and that's exactly why I dropped the idea of using NDATA_VALID in bit 31 of flags, and switched to a capability instead. If it is desirable for Android, crosvm can "quirk" that ARM always has valid data[0]. Paolo > I'd like to see a full series that implements the transition before we > make a decision on this.