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Mon, 19 May 2025 05:25:38 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 19 May 2025 14:25:36 +0200 Message-Id: Subject: Re: [PATCH v3 1/2] RISC-V: KVM: add KVM_CAP_RISCV_MP_STATE_RESET Cc: , , , , "Atish Patra" , "Paul Walmsley" , "Palmer Dabbelt" , "Albert Ou" , "Alexandre Ghiti" , "Andrew Jones" To: "Anup Patel" From: =?utf-8?q?Radim_Kr=C4=8Dm=C3=A1=C5=99?= References: <20250515143723.2450630-4-rkrcmar@ventanamicro.com> <20250515143723.2450630-5-rkrcmar@ventanamicro.com> In-Reply-To: 2025-05-16T17:55:05+05:30, Anup Patel : > On Thu, May 15, 2025 at 8:22=E2=80=AFPM Radim Kr=C4=8Dm=C3=A1=C5=99 wrote: >> >> Add a toggleable VM capability to reset the VCPU from userspace by >> setting MP_STATE_INIT_RECEIVED through IOCTL. >> >> Reset through a mp_state to avoid adding a new IOCTL. >> Do not reset on a transition from STOPPED to RUNNABLE, because it's >> better to avoid side effects that would complicate userspace adoption. >> The MP_STATE_INIT_RECEIVED is not a permanent mp_state -- IOCTL resets >> the VCPU while preserving the original mp_state -- because we wouldn't >> gain much from having a new state it in the rest of KVM, but it's a very >> non-standard use of the IOCTL. >> >> Signed-off-by: Radim Kr=C4=8Dm=C3=A1=C5=99 >> --- >> If we want a permanent mp_state, I think that MP_STATE_UNINITIALIZED >> would be reasonable. KVM could reset on transition to any other state. > > Yes, MP_STATE_UNINITIALIZED looks better. I also suggest > that VCPU should be reset when set_mpstate() is called with > MP_STATE_UNINITIALIZED and the current state is > MP_STATE_STOPPED. That would result in two resets (stopped -> uninitialized -> *), unless we changed the logic. Would you prefer to reset on transition to the new permanent mp_state? MP_STATE_INIT_RECEIVED seems a more fitting name for the state, then. Thanks.