From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0A71010E9 for ; Wed, 17 Sep 2025 23:02:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758150134; cv=none; b=vCS2ui+FHO9ScXLQFnp1bo3HoyQRxWXCR9L8wWOaHOlTV6o/TojB1jUygKe+QL/MPRwJmjRk9AOzXRpewk3FXKWrLHbOd0Uy3ZR19pKIomEwyPeCdCG+2FxOpGCbtzHo7cGyIC0JH29GvvBMNvFqKzSmTBl37MiH8MMyBDPVW1w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758150134; c=relaxed/simple; bh=z9jj/dh0S6W2eXpDU5Up7mrUC508ERUUksMpIvjvSDc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=J5UC5K0BivzDtpeDQOKbuvLqP8pfU/HxShMXzjLcEbrl+kSxhhAcQRlHW1JujJfaeg7SxQDoR5OPvDnnU7tE/5GQ7Md+GfCtgP0EEiboibypQFIleXyLGoJY9FfQwAoiemezTysTRti6I5r7yUh5Y/Hk6lxWseKd0qvnNmcEfKU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=VmfspLlD; arc=none smtp.client-ip=209.85.216.74 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="VmfspLlD" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-329dca88b5aso1524210a91.1 for ; Wed, 17 Sep 2025 16:02:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1758150132; x=1758754932; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=uXvv08vlixvMjyF5WhKNg9FBBdv11ZBTjvJpc8LmO1w=; b=VmfspLlD3G1KH3N9KJ1jNlFurUd1C85SDebTmy2poYgXVKg/LXnR+YaB/xWOd1O6MQ MduFC9Wkk8gUEglRIMJWgbjV14iSBkoKeA0AvdLfnVkyGj/snS+XuYSJavgsANKYecxz 0RpelMdK3AlF44K1Izkujvd5Pu2tVK2WN+z+CSBrNFbsHSLizVsO6T2phYksjY3ggKiO NI8IpKLXYKYBsxbeu1FRPlgc2Q/Nhtvlc3y/oSIj0ulpKx52t3zHDt2GRshz5zguoTXe fY1ZlUjpRh8cYXGtR40DNUGaiO+nF+hPzsbJXbDU+voaFtdpOkTXEsc1U48oDYpmO6AS oZJQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758150132; x=1758754932; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=uXvv08vlixvMjyF5WhKNg9FBBdv11ZBTjvJpc8LmO1w=; b=WzPSSd36GfgRbux4VCL5lgbknmQ6vU3nGZKjdhJdtrlt6HB2sKIrrvOVShA4hoVTB3 ZZ59X27RfNBxB+Bq71MZArC4qOJ7Q35eL1FbUofW76oIFmkgXXqDnOpXsgG36uMISrwm eCeN8pFirg3ei3qOqj8LaLao1Og7fzkzQ2veOEuPne8LSKmTxOZqcXB13yt1i05dHEPG Hb49eH/rVcdK5Cs+0dcCK7rTRf7REzG8mpnIJiBLPIfDWOV9510GtsA+0JDtK4WCAtZT C3tZkVnBsj404V4/7C7SV8QRO4YP/QQyEmoSXi7ULgVys78MYM4VGmZskP/1XnM5jOdQ YMNg== X-Forwarded-Encrypted: i=1; AJvYcCXzLwE20TZy5zD/YeOVNpBiyktx5B/wfvVJgBABQvA4yY5omljOLaRiJOnotZJ5kYkX1dc=@vger.kernel.org X-Gm-Message-State: AOJu0Yx43iExhPtj1SVyrhgPeGzuzDF3iytO0Axj5M5ndCyd86s27kN6 S0MY4ZePXbK2VgTjQ330lairQsf8dravBzZWcdbVN+vvUquvNsYWDR42L7Zn03NGVprVO04Ft8d IGRzvQQ== X-Google-Smtp-Source: AGHT+IEmHTqPKDw85gYpQLyZoWz4mHqPlxsjsZ3kfl9YZfHWLosdKTXZ1EF54fp4ZzNMDipJWOGGvUoBfQY= X-Received: from pjkk4.prod.google.com ([2002:a17:90b:57e4:b0:327:e021:e61d]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1a84:b0:32e:3592:581a with SMTP id 98e67ed59e1d1-3305c6e438emr1476768a91.17.1758150132332; Wed, 17 Sep 2025 16:02:12 -0700 (PDT) Date: Wed, 17 Sep 2025 16:02:11 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250909182828.1542362-1-xin@zytor.com> <20250909182828.1542362-6-xin@zytor.com> Message-ID: Subject: Re: [RFC PATCH v1 5/5] KVM: Remove kvm_rebooting and its references From: Sean Christopherson To: Xin Li Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, linux-pm@vger.kernel.org, pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, rafael@kernel.org, pavel@kernel.org, brgerst@gmail.com, david.kaplan@amd.com, peterz@infradead.org, andrew.cooper3@citrix.com, kprateek.nayak@amd.com, arjan@linux.intel.com, chao.gao@intel.com, rick.p.edgecombe@intel.com, dan.j.williams@intel.com Content-Type: text/plain; charset="us-ascii" On Wed, Sep 17, 2025, Xin Li wrote: > On 9/16/2025 10:56 AM, Sean Christopherson wrote: > > On Tue, Sep 09, 2025, Xin Li (Intel) wrote: > > > Drop kvm_rebooting and all related uses. Virtualization is now disabled > > > immediately before a CPU shuts down, eliminating any chance of executing > > > virtualization instructions during reboot. > > > > Wrong. KVM clears EFER.SVME in reponse to kvm_shutdown(), and thus can trip > > #UDs on e.g. VMRUN. > > > > This patch assumes that AMD SVM enable/disable has been moved to the CPU Ah, that wasn't exactly obvious. > startup and shutdown routines. Accordingly, kvm_shutdown() no longer clears > EFER.SVME, and the patch demonstrates the resulting simplification from > removing kvm_rebooting. However, as noted in the cover letter, no actual > modifications were made to AMD SVM. Heh, yeah, that's what's wrong.