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 1AB872D5923 for ; Wed, 25 Feb 2026 20:21:10 +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=1772050871; cv=none; b=SyaVigka8GesU53GuQc+rKjbwCFRIymvJ59guP6VNP9TwfdCrUZPRzCuaRui3ZS+KeKkXdfYr9Q2GxqIX71DU0dcjKJSzm1Hn3/2GYwV1bTC0F4JW2A62kZXsKXZHfTaeaO3QzQsyIWiLCSKGZoI6ssZQvDQkLH5DfaTtCwnrmE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772050871; c=relaxed/simple; bh=CjFbqOLn5WP5KXf0R1Hc9sBVWXyOe7id4YswrRUGc7w=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=osVefgdwY7xI/pvmzc08IEiyxqsh4CESfx6eQtcaEMU+k76eaklG6R7Zr8Fvc7ovvKIURX6Hs6188Jc+IvI3snt9MVXJ4JRioB4+ZutfvYdNJ9WUlXhlSNlm8dgvk+MgHSvLx8XoHttcBUOuC7YCVQl4mtubQ8yjZBt2qreBLdM= 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=uTDMm2rc; 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="uTDMm2rc" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-35449510446so7007685a91.0 for ; Wed, 25 Feb 2026 12:21:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1772050869; x=1772655669; 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=ldmr9oU0MSeitk+1OIgY+rdK40ygdsN3dEDub2L4tpc=; b=uTDMm2rcxuJbh1kxaJFRzKifwMm+9jSmvILj3cg4QiwiJm7hZ7wREYQRdJghKYC6cl wmH7EYGcUNrLdS4e2CyNTxFU44ZKc/4Afo55cOREdwM+H5y9L74+um7RVtsowjNExGQI QVmCl99HjMyy1viLIVoijzpQqOYbgcEemkNFfgwHMh3X5qsbuRyR0W+cfRgyqGRUpFm2 w9iIriqBETT/liunHaGgFRsKGTpJgDp0y6N+ia02/tvgM26ooMe6xnwoZatZpRF4lRAn o8PYQgYgaF3AJWSNbU3rlqB2jW0sKF7xtlFa6rep7SpxspYBa54Qv7FB7BDgKqaGKLMx Y/Dg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1772050869; x=1772655669; 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=ldmr9oU0MSeitk+1OIgY+rdK40ygdsN3dEDub2L4tpc=; b=FD9HUbQPZKAN3r9pDkwirX4CtIwaNOLHM3HLSZDii18QILSH8z8q4uoy5i+xe3ffwf zdXqsCj/7YrhPpN/nKaRLoJybRBJ1cZn1yRW+EIXh74VJ6oq9+mdzV8VYIZ8MWPg58X/ uvdrGEGR/mZtHj+8co01nByeWThqb/TnPq4n/MpY0n6fohwrLoZZJv7a3QkbcqpayHls 9d+g+qTK0m6FqsFFFkSg1dbCcB3QcxY4BL1cAyiJKPXKIj1r5AHvAgb4/iKFTvPa/E9w kXHg2otytYNnB5hwR7ffQ3qjZ2HVZJ275+9ra6NTgQPPmu8Bj2IE0hhkPVfuOpK2dGKy 02zg== X-Forwarded-Encrypted: i=1; AJvYcCXxM5k1v5v5Ki3S1NNiFZp6BcHUmaPQeUY5BfDLACf27f83z6KJUedJrrYRG8vyJxJJSzhSHaJA/Ym93hU=@vger.kernel.org X-Gm-Message-State: AOJu0YxIBXrPs8ekytebolSvxxanU6pxHmA6mpbWqCi0l9ZEFossqkO5 A5BI86C3ZCICTcSIoSs4RZjoL9Y6Kb0vmYbLBr3FOwSpg0diIQZseb9cSNBjKOke6NohlBWUmST HZclDNw== X-Received: from pjbsl11.prod.google.com ([2002:a17:90b:2e0b:b0:34e:90d2:55c0]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:2812:b0:354:a9f3:68bc with SMTP id 98e67ed59e1d1-358ae8e8390mr13614658a91.30.1772050869370; Wed, 25 Feb 2026 12:21:09 -0800 (PST) Date: Wed, 25 Feb 2026 12:21:07 -0800 In-Reply-To: <928a31e1-bb6f-44d4-b1de-654d6968fd55@fortanix.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <928a31e1-bb6f-44d4-b1de-654d6968fd55@fortanix.com> Message-ID: Subject: Re: [PATCH] KVM: SEV: Track SNP launch state and disallow invalid userspace interactions From: Sean Christopherson To: Jethro Beekman Cc: Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev Content-Type: text/plain; charset="us-ascii" On Wed, Feb 25, 2026, Jethro Beekman wrote: > On 2026-02-25 12:05, Sean Christopherson wrote: > > On Mon, Jan 19, 2026, Jethro Beekman wrote: > >> Calling any of the SNP_LAUNCH_ ioctls after SNP_LAUNCH_FINISH results in a > >> kernel page fault due to RMP violation. Track SNP launch state and exit early. > > > > What exactly trips the RMP #PF? A backtrace would be especially helpful for > > posterity. > > Here's a backtrace for calling ioctl(KVM_SEV_SNP_LAUNCH_FINISH) twice. Note this is with a modified version of QEMU. > RIP: 0010:sev_es_sync_vmsa+0x54/0x4c0 [kvm_amd] > snp_launch_update_vmsa+0x19d/0x290 [kvm_amd] > snp_launch_finish+0xb6/0x380 [kvm_amd] > sev_mem_enc_ioctl+0x14e/0x720 [kvm_amd] > kvm_arch_vm_ioctl+0x837/0xcf0 [kvm] Ah, it's the VMSA that's being accessed. Can't we just do? diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index 723f4452302a..1e40ae592c93 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -882,6 +882,9 @@ static int sev_es_sync_vmsa(struct vcpu_svm *svm) u8 *d; int i; + if (vcpu->arch.guest_state_protected) + return -EINVAL; + /* Check some debug related fields before encrypting the VMSA */ if (svm->vcpu.guest_debug || (svm->vmcb->save.dr7 & ~DR7_FIXED_1)) return -EINVAL;