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[35.185.214.157]) by smtp.gmail.com with ESMTPSA id w6sm3852283pfj.179.2021.09.30.10.19.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 30 Sep 2021 10:19:21 -0700 (PDT) Date: Thu, 30 Sep 2021 17:19:18 +0000 From: Sean Christopherson To: Marc Zyngier Subject: Re: [PATCH v2 06/11] KVM: arm64: Add support for SYSTEM_SUSPEND PSCI call Message-ID: References: <20210923191610.3814698-1-oupton@google.com> <20210923191610.3814698-7-oupton@google.com> <877deytfes.wl-maz@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <877deytfes.wl-maz@kernel.org> Cc: Peter Shier , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Thu, Sep 30, 2021, Marc Zyngier wrote: > Hi Oliver, > > On Thu, 23 Sep 2021 20:16:05 +0100, > Oliver Upton wrote: > > > > ARM DEN0022D 5.19 "SYSTEM_SUSPEND" describes a PSCI call that may be > > used to request a system be suspended. This is optional for PSCI v1.0 > > and to date KVM has elected to not implement the call. However, a > > VMM/operator may wish to provide their guests with the ability to > > suspend/resume, necessitating this PSCI call. > > > > Implement support for SYSTEM_SUSPEND according to the prescribed > > behavior in the specification. Add a new system event exit type, > > KVM_SYSTEM_EVENT_SUSPEND, to notify userspace when a VM has requested a > > system suspend. Make KVM_MP_STATE_HALTED a valid state on arm64. > > KVM_MP_STATE_HALTED is a per-CPU state on x86 (it denotes HLT). Does > it make really sense to hijack this for something that is more of a > VM-wide state? I can see that it is tempting to do so as we're using > the WFI semantics (which are close to HLT's, in a twisted kind of > way), but I'm also painfully aware that gluing x86 expectations on > arm64 rarely leads to a palatable result. Agreed, we literally have billions of possible KVM_MP_STATE_* values, and I'm pretty sure all of the existing states are arch-specific. Some are common to multiple architectures, but I don't think _any_ are common to all architectures. _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm