From nobody Mon Feb 9 05:59:25 2026 Received: from mail-pf1-f202.google.com (mail-pf1-f202.google.com [209.85.210.202]) (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 2C7E628853C for ; Wed, 14 May 2025 18:41:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747248117; cv=none; b=mcy2FpZ0Bp6/LhcKD6PgLF+Kmort4+jg1i4+V4r+LY4eYjo5gO0j3vkHcTzt89NWejunN+tYuyjpFa0Ei2nIV5JWgPsVYk8P67Hn1Oyxxx/1boOt2wHQxKSvalpGrB3050F9y9SHJ7LBhGvwJZSYbhBT+v5PcLdY1qEwSYDnCmo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747248117; c=relaxed/simple; bh=2O407uN7TPj25b78VqtGudUAcYRMX6ZZFh6qGZMf62g=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=VWnVcZzzZOkrYiqPrkxYeXCON1TWszxdKGLnogxkdGHjUri/3rUAF379lOv2iSzCck+bjee9xp2GJWIuGK64Hbg8KBajfWuNVaX64OYvx5JPrJUZmotX6K7+a9n45MxfGb0RyeAwkfJD4aRCELCgvf2+furYcxkHqA/c8qzsHiw= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--dionnaglaze.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=bKsVEnG+; arc=none smtp.client-ip=209.85.210.202 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--dionnaglaze.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="bKsVEnG+" Received: by mail-pf1-f202.google.com with SMTP id d2e1a72fcca58-740adfc7babso164956b3a.0 for ; Wed, 14 May 2025 11:41:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1747248116; x=1747852916; 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=QvCauuU2L9CGciSBd5j7n776p/pTGMk1tOvrluwsTQo=; b=bKsVEnG+vvBag+77Mu037rJ3BA+ea5Vu/BPF8y/FiNNFT1APwolHZtCHy3g8xI3sAp do81ent+2acVws5rD/VDB8wLKCQfxKEXyzIGL2IRyx+wi9fRZQXNDoSbCYNFefitCpw2 /uv8ZKiAr/08plgbfL7YQXPcsuZlAXz4qMt3OVwBPne+v8nD+QxQu5Gfp6A5xyJ6ICu/ m3BtL3ct3HFBZcot1ByAe3sPcY22XCs2wlhcaSNubf8V3vL+365QVbIs2qdrjOH/zEH5 2/JFuk2NdOCeSwcSR8RYoSMPyX9Xh6fK+B2mi9FmrYivouB/5HlOoK1CVoGOLUGX9Y9O hXOA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1747248116; x=1747852916; 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=QvCauuU2L9CGciSBd5j7n776p/pTGMk1tOvrluwsTQo=; b=deoEOun4jJsJCX93q3/rlYjqH07oCwpkO1zhpLSM0ZVNFSwSHy76Z4BJsIvJ7Kv0uI fsrcR6TaZNPFOIZfVigpXxuAmamTSCJl3jMRM6ZIpXYFofDDMQVHv35jHomLKvK5xtVA MGgjrP1rDxEBDGW0YUl01XbjlAMTevHLZugRYB2G9Ub6GUN+jJvd+ER7d6EbACZyBmhh WydFYyg3yBaFZN63X5qhggBPXv/rznApD3HeERo0+oZqKnE+VRkAaOKde+kakEg5iW77 FSBkLHg00W/ht2RVOPv9zdeSTLowdKDZl/WKv8LRty8L4iSRbMt4apiLsvcMojrsNxsd w7xg== X-Gm-Message-State: AOJu0YyFi+tF21vY8ac1guexMDTjxf0IiTgmRmJANqTwG09sV/ISPKqg s7K6xdNnlk2PuyY+oaxdoFZo6Uji1bYEgW+StG/+Iv+oTVYwgBrICH2xWSlohc0KvjBN5/cAqnb ALh6BSwDYqIlrMGN/r9GXYg== X-Google-Smtp-Source: AGHT+IHAyCtpbaFX2wLqdc+E6NWHdYXGqYB3sKBEGQUjo89w5UgIHgCaHe6vWLT29dng2koFOR7LeCkZ+D5XCeyATw== X-Received: from pgc11.prod.google.com ([2002:a05:6a02:2f8b:b0:b14:df7a:ff1]) (user=dionnaglaze job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a21:62cc:b0:215:d4be:b0b1 with SMTP id adf61e73a8af0-215ff194479mr8038203637.32.1747248115718; Wed, 14 May 2025 11:41:55 -0700 (PDT) Date: Wed, 14 May 2025 18:41:35 +0000 In-Reply-To: <20250514184136.238446-1-dionnaglaze@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250514184136.238446-1-dionnaglaze@google.com> X-Mailer: git-send-email 2.49.0.1045.g170613ef41-goog Message-ID: <20250514184136.238446-3-dionnaglaze@google.com> Subject: [PATCH v4 2/2] kvm: sev: If ccp is busy, report busy to guest From: Dionna Glaze To: kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, Dionna Glaze , Thomas Lendacky , Paolo Bonzini , Joerg Roedel , Peter Gonda , Borislav Petkov , Sean Christopherson Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The ccp driver can be overloaded even with guest request rate limits. The return value of -EBUSY means that there is no firmware error to report back to user space, so the guest VM would see this as exitinfo2 =3D 0. The false success can trick the guest to update its message sequence number when it shouldn't have. Instead, when ccp returns -EBUSY, that is reported to userspace as the throttling return value. Cc: Thomas Lendacky Cc: Paolo Bonzini Cc: Joerg Roedel Cc: Peter Gonda Cc: Borislav Petkov Cc: Sean Christopherson Signed-off-by: Dionna Glaze --- arch/x86/kvm/svm/sev.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c index febf4b45fddf..c1bd82c26a11 100644 --- a/arch/x86/kvm/svm/sev.c +++ b/arch/x86/kvm/svm/sev.c @@ -4061,6 +4061,11 @@ static int snp_handle_guest_req(struct vcpu_svm *svm= , gpa_t req_gpa, gpa_t resp_ * the PSP is dead and commands are timing out. */ ret =3D sev_issue_cmd(kvm, SEV_CMD_SNP_GUEST_REQUEST, &data, &fw_err); + if (ret =3D=3D -EBUSY) { + svm_vmgexit_no_action(svm, SNP_GUEST_ERR(SNP_GUEST_VMM_ERR_BUSY, fw_err)= ); + ret =3D 1; + goto out_unlock; + } if (ret && !fw_err) goto out_unlock; =20 --=20 2.49.0.1045.g170613ef41-goog