From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CCFDC49A3C3 for ; Mon, 21 Sep 2026 12:35:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789994150; cv=none; b=oYGzGJ+5Ab+W5F0M+2/eWVZv/hk8z9HNQUnDnhGSS4nQdB+J8wHJO15s/FrFNyntGy8U3LHOuvlhcZCPtgBdleA1kgmnd4/gECndNCRtHxrjINTaq6qLqHezDoSJVzr02rub/GCcWMNz337TNMTnLuaRPLwFloZO0f3u+NsxhRo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789994150; c=relaxed/simple; bh=1KvxwuS25EF/no5Z1pi9py0qFAxICp2dtM3rPiWavlo=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=mNHH5Q09v/1srde8pbyGRVnedpJ3s7aLZvGW4aG2hCKsur/nQwhZZaNg+jA19belC0Oxatz3VAdppB0xLj21toXaQUP6p/+EwV9Hj2Rz98OYc96lk8x5ud2NWO9RTp30/ncrzYdNet9qMYbicjRUV2vdbpLQhbOAqCeQ3peCdGk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fcpp9gmM; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fcpp9gmM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1BC71F000FF; Mon, 21 Sep 2026 12:35:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789994144; bh=iq3gn4TNcPDE4jh+Ou5pfKzJP4f+ZQ0NOW1KANzi6lQ=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=fcpp9gmMkBZ7TPiGQM/fPJ74PC9+QIL0C31rq0xYnMAOBivDTVYtyOs7dxCSCTEPD x/v3YRVZYPk5RPtgU8Ho2fA6EaNfMArHrorGxTGZCdJHegB8E+Riugc3YPrMQqwqq1 oiVMJbEDH4+wEpNmH5A8gTfw0QqBJ8MUCIAv83yTdU5qIdsz9jhepL2icG0c7bV+J6 KSZVo0XixdYWdF/cOcsTmJljOfB+ZmRKHrp8ZEWvqfeQFdqqP12ZAH2bV+QVvgh+zz b4Hxc1BKzVmrDQdxw4/ln01ZlQrPM0/+fEw0pxE+yzSub39NrwEIXCcF+OLgJvEiiu dUkHjCskqYCqw== From: sashiko-bot@kernel.org Subject: Re: [PATCH RFC v4 1/4] RISC-V: paravirt: Add pvqspinlock KVM backend Reply-To: sashiko-reviews@lists.linux.dev To: =?utf-8?b?R1VPIFJlbiAoWHVhblRpZSk=?= Cc: kvm@vger.kernel.org In-Reply-To: <20260921-pvqspinlock-v4-1-409a22aed6ef@kernel.org> References: <20260921-pvqspinlock-v4-0-409a22aed6ef@kernel.org> <20260921-pvqspinlock-v4-1-409a22aed6ef@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Mon, 21 Sep 2026 12:35:44 +0000 Message-Id: <20260921123544.A1BC71F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Thank you for your contribution! Sashiko AI review found 1 potential issue(= s) to consider: - [Critical] kvm: new SBI_EXT_PVLOCK extension is enabled by default breaki= ng migration -- commit f1e45d3725cd5aab3846041669bc52a712a0d928 Author: GUO Ren (XuanTie) RISC-V: paravirt: Add pvqspinlock KVM backend Add the KVM backend for the SBI PVLOCK (paravirt qspinlock kick_cpu) extension. kvm_sbi_ext_pvlock_kick_cpu() kicks the target vCPU out of the halted state via kvm_vcpu_kick(), and yields to it with kvm_vcpu_yield_to() when the target is already runnable. > diff --git a/arch/riscv/kvm/vcpu_sbi_pvlock.c b/arch/riscv/kvm/vcpu_sbi_p= vlock.c > new file mode 100644 > index 0000000000000..728e59f3f18fb > --- /dev/null > +++ b/arch/riscv/kvm/vcpu_sbi_pvlock.c [ ... ] > +const struct kvm_vcpu_sbi_extension vcpu_sbi_ext_pvlock =3D { > + .extid_start =3D SBI_EXT_PVLOCK, > + .extid_end =3D SBI_EXT_PVLOCK, > + .handler =3D kvm_sbi_ext_pvlock_handler, > +}; [Severity: Critical] Does this extension need to be disabled by default to prevent ABI breakage? Since vcpu_sbi_ext_pvlock omits .default_disabled, it evaluates to false, causing KVM to default the extension to KVM_RISCV_SBI_EXT_STATUS_ENABLED during VM initialization. Silently enabling new guest-visible KVM features breaks live migration. Migrating the VM to an older host kernel without this feature will cause the guest to crash when it attempts to use the extension. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260921-pvqspinloc= k-v4-0-409a22aed6ef@kernel.org?part=3D1