From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (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 512213ED11C for ; Mon, 9 Mar 2026 18:57:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773082658; cv=none; b=dMlJ4olyMRG9jM0bPIrw/V2w9UKgnXuEknZ8/q4S/mq7FL3VBLOQ/Ob7YSOR6gbubx2TFUiNvqvvfJBrRytiRbHjRpkRjSYsx9/gZXkyyt6P8nKK+v9yjbsZD2QnIFtKDXXo4FTfGUqG02go1KokBOTKDT88yA9MeYo3WDqYJKY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773082658; c=relaxed/simple; bh=2sWkcshK8v9D9vZK4BwTmxDn77rNBZdLtVxpuqk0RrU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=ZVnAbBX8Ipgv7otz8v7/z2v3q8pcVtIZa5wDiTX0OScb2TCOMgTqvt/VjnALrmR0EX1lrv2GltUgTY5RHEipp3KM6LkFLEjSpgVcVYZ7PCio9a0LjHUKRNrWJnn1Lt3youzgyuMO8Mcrp0cGW/4p04NwKf85vjkkSuWtAH7CYyo= 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=0JkiFkar; arc=none smtp.client-ip=209.85.215.202 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="0JkiFkar" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-c7380305a9aso3390844a12.1 for ; Mon, 09 Mar 2026 11:57:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1773082657; x=1773687457; 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=cu18vwk9wqpfrSC1zqzF0tmbP6f6cCnfxRa9hLjD9hI=; b=0JkiFkar+FAJM1fwAtfw3odRTdVNlNnqPEr8NztkEJRZrxavVSxlIs6bMVew84gvzA WGOuFRZDYhegDkOGdc8+qlZIRr5LVQuuuVYJbIp1FEo6H1Fti9cJ8isRk5Bqwppg2oKu eh3yCv3kWq7Ez9NhYuWki4lTU+7aeybTYfKbVUJiwudnWoq22+UV+1cww8Bh4H/qoFz7 KgGSD6tB0Nfhr6IWeo1Nm9UUXLd7KYtN3kUwRzLYeDrSYzNyfIGkmVMXcfl1nkV/JOI6 aFvW53P0jfGSw5O7Sx4E9Ob8ro6+/N2bkTIwr8TPHFW7d+QZahwFHipWarfURn+pTvef wDyA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1773082657; x=1773687457; 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=cu18vwk9wqpfrSC1zqzF0tmbP6f6cCnfxRa9hLjD9hI=; b=YwjsAKLm6llS98+SlQdyEkns9MmaEpEMLZwqub0TR7QvA5PRiemOJZvmT+8Mp2oemi 8IYd5JKCWY8/OcxTH68DzD3jYUjcBQ5gNkeoVnVdgi8oe0c5Nb7zXQzjhfLdpEL0F1Jn hH34K3UdmwIm+karcrRUksUYfkluEaoErXVgmXP9/jIoT/NUyvBXrrComlX8VxV/d7si RjWJs2VllwznUnoe4t4OmJ3x7WxGQqDwwTsGEvOR+yK3q4au4YhO1uUDUTCveZexU3yG HT4n0xwPoo/IlgOKeE62XG5FmrbwopAbQ6Tv+PCMfjbmIAEtaO9LNmE4riqopEiKvFE0 f4dw== X-Forwarded-Encrypted: i=1; AJvYcCXqPVIjO6Jpfkk/7TUch0KjB2ncenC0IEb787unFZFgRB1AWV07CFt0YSmtGK6aDr1uZmFpGNHNkZJIZ2Y=@vger.kernel.org X-Gm-Message-State: AOJu0Yx7ls1Zp/E/IMnnY8GngBVAEEjRki7ia/+QD3zuzEyIuKgzZ7ge Yy9hhgFQ6GwiOoDUK/RwuwQUeF9xb12MqX49BHfyirdv9f6bbeU2Nguto8dGSGfTJyWRGjt13JW grX4wEw== X-Received: from pgbdk2.prod.google.com ([2002:a05:6a02:c82:b0:c73:90cf:9638]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:164a:b0:398:5f66:bf59 with SMTP id adf61e73a8af0-398ab4e40e9mr518308637.36.1773082656530; Mon, 09 Mar 2026 11:57:36 -0700 (PDT) Date: Mon, 9 Mar 2026 11:57:35 -0700 In-Reply-To: <7c5d0db9-5151-4edb-9b97-0f0b268cf36e@amd.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260129063653.3553076-1-shivansh.dhiman@amd.com> <20260129063653.3553076-2-shivansh.dhiman@amd.com> <7c5d0db9-5151-4edb-9b97-0f0b268cf36e@amd.com> Message-ID: Subject: Re: [PATCH 1/7] KVM: SVM: Initialize FRED VMCB fields From: Sean Christopherson To: Shivansh Dhiman Cc: pbonzini@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, xin@zytor.com, nikunj.dadhania@amd.com, santosh.shukla@amd.com Content-Type: text/plain; charset="us-ascii" On Mon, Mar 09, 2026, Shivansh Dhiman wrote: > Hey Sean, > > On 07-03-2026 07:28, Sean Christopherson wrote: > > On Thu, Jan 29, 2026, Shivansh Dhiman wrote: > >> From: Neeraj Upadhyay > >> > >> The upcoming AMD FRED (Flexible Return and Event Delivery) feature > >> introduces several new fields to the VMCB save area. These fields include > >> FRED-specific stack pointers (fred_rsp[0-3], fred_ssp[1-3]), stack level > >> tracking (fred_stklvls), and configuration (fred_config). > >> > >> Ensure that a vCPU starts with a clean and valid FRED state on > >> capable hardware. Also update the size of save areas of VMCB. > > > >> diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c > >> index f4ccb3e66635..5cec971a1f5a 100644 > >> --- a/arch/x86/kvm/svm/svm.c > >> +++ b/arch/x86/kvm/svm/svm.c > >> @@ -1110,6 +1110,16 @@ static void init_vmcb(struct kvm_vcpu *vcpu, bool init_event) > >> save->idtr.base = 0; > >> save->idtr.limit = 0xffff; > >> > >> + save->fred_rsp0 = 0; > >> + save->fred_rsp1 = 0; > >> + save->fred_rsp2 = 0; > >> + save->fred_rsp3 = 0; > >> + save->fred_stklvls = 0; > >> + save->fred_ssp1 = 0; > >> + save->fred_ssp2 = 0; > >> + save->fred_ssp3 = 0; > >> + save->fred_config = 0; > > > > Is this architecturally correct? I.e. are all the FRED MSRs zeroed on INIT? > > Yes that's right, the FRED MSRs are zeroed on init. Please use that as the basis for the changelog. "Ensure that a vCPU starts with a clean and valid FRED state on capable hardware" is largely meaningless because vCPU structures are zero-allocated.