From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 1E9D93E3C69; Mon, 4 May 2026 16:52:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777913538; cv=none; b=brm1pGoWvAJhe397SIVPugQ5E4A3X8xZ8cOuzEu6M9fENZmPPi2fWBzhrxUhaVKFO5joMGdaA8AlVsYD2cLTCEG6p7Kh6TGuoU47nLGGDZknyMpdst25aCL9gMyiOUZ8KhQmkozLmZYxuL4GBtKIR3k0HBV9FOaQzJW2xOSYfwU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777913538; c=relaxed/simple; bh=Fw7svH/liofO4kK7H0XxtvP07i4I2IoOHIbSEEO2pUE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Yx1DYlVd3RdRy9txe5JDFTGqLLx+mv2cN/hAeDbYnpNiKFSIIDvNkVXViShU7MF7eEqyQKjMIps2pZCoKyeeXyIIDHiCI+Rl5i5POhUazpfGh8FRBBn6xE73qnivApepYzjXZA9qx11cyBmEyAjZYBDYHDojfcYUrrbAgjuzWQM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YIC7msaE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YIC7msaE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 970AEC2BCC4; Mon, 4 May 2026 16:52:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777913537; bh=Fw7svH/liofO4kK7H0XxtvP07i4I2IoOHIbSEEO2pUE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YIC7msaEJqzjuUdGOvWonpjck6LcAUPwDpqJWnKoYPnAbQOUNyK80/4bRbAXFhpND 0gbhYkeZOH6sWURLwUEVd5yUnEfV73sobDXdIgNZ0bcxFEmoCVaQuei0gr9eZKF32Z Th6kiYIwYPW/jVLI+meNn5K09EjMxzkOarXvuS2uZr1fYnyL6TihgZivmiYmW+bc/o bdWYllnEpgiiPBHb5X2vI3hzSJzvf4HVq4V1Y4G03Ne+iw2WUpgBy5O7g/M/EECt1S ZFTtqUEvFXVYGhIredWFkyEJ+q1WRD6cFqR/iKgyXubGTCjpi0yhF2vRL+0cE2K6pI 9zfWur7PNCazA== From: Tycho Andersen To: Tom Lendacky , John Allen , Herbert Xu , "David S. Miller" , Ashish Kalra Cc: "Borislav Petkov (AMD)" , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, Brijesh Singh , Michael Roth , Alexey Kardashevskiy , Dan Williams , "Tycho Andersen (AMD)" , stable@vger.kernel.org Subject: [PATCH v2 4/4] crypto/ccp: Do not initialize SNP for ioctl(SNP_CONFIG) Date: Mon, 4 May 2026 10:51:47 -0600 Message-ID: <20260504165147.1615643-5-tycho@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260504165147.1615643-1-tycho@kernel.org> References: <20260504165147.1615643-1-tycho@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: "Tycho Andersen (AMD)" Sashiko notes: > if SEV initialization fails and KVM is actively running normal VMs, could a > userspace process trigger this code path via /dev/sev ioctls (e.g., > SEV_PDH_GEN) and zero out MSR_VM_HSAVE_PA globally? Would the next VMRUN > execution for an active VM trigger a general protection fault and crash the > host? Refuse to re-try initialization if SNP is not already initialized for SNP_CONFIG. This is technically an ABI break: before if SNP initialization failed it could be transparently retriggered by this ioctl, and if no VMs were running, everything worked fine. Hopefully this is enough of a corner case that nobody will notice, but someone does, there are a few options: * do something like symbol_get() for kvm and refuse to initialize if KVM is loaded * check each cpu's HSAVE_PA for non-zero data before re-initializing * once initialization has failed, continue to refuse to initialize until the ccp module is unloaded Fixes: ceac7fb89e8d ("crypto: ccp - Ensure implicit SEV/SNP init and shutdown in ioctls") Reported-by: Sashiko Assisted-by: Gemini:gemini-3.1-pro-preview Link: https://sashiko.dev/#/patchset/20260324161301.1353976-1-tycho%40kernel.org CC: Signed-off-by: Tycho Andersen (AMD) --- drivers/crypto/ccp/sev-dev.c | 33 ++++----------------------------- 1 file changed, 4 insertions(+), 29 deletions(-) diff --git a/drivers/crypto/ccp/sev-dev.c b/drivers/crypto/ccp/sev-dev.c index ad6c2525a305..7c4dd57fabb9 100644 --- a/drivers/crypto/ccp/sev-dev.c +++ b/drivers/crypto/ccp/sev-dev.c @@ -1727,21 +1727,6 @@ static int sev_move_to_init_state(struct sev_issue_cmd *argp, bool *shutdown_req return 0; } -static int snp_move_to_init_state(struct sev_issue_cmd *argp, bool *shutdown_required) -{ - int error, rc; - - rc = __sev_snp_init_locked(&error, 0); - if (rc) { - argp->error = SEV_RET_INVALID_PLATFORM_STATE; - return rc; - } - - *shutdown_required = true; - - return 0; -} - static int sev_ioctl_do_reset(struct sev_issue_cmd *argp, bool writable) { int state, rc; @@ -2451,8 +2436,6 @@ static int sev_ioctl_do_snp_set_config(struct sev_issue_cmd *argp, bool writable { struct sev_device *sev = psp_master->sev_data; struct sev_user_data_snp_config config; - bool shutdown_required = false; - int ret, error; if (!argp->data) return -EINVAL; @@ -2460,21 +2443,13 @@ static int sev_ioctl_do_snp_set_config(struct sev_issue_cmd *argp, bool writable if (!writable) return -EPERM; + if (!sev->snp_initialized) + return -ENODEV; + if (copy_from_user(&config, (void __user *)argp->data, sizeof(config))) return -EFAULT; - if (!sev->snp_initialized) { - ret = snp_move_to_init_state(argp, &shutdown_required); - if (ret) - return ret; - } - - ret = __sev_do_cmd_locked(SEV_CMD_SNP_CONFIG, &config, &argp->error); - - if (shutdown_required) - __sev_snp_shutdown_locked(&error, false); - - return ret; + return __sev_do_cmd_locked(SEV_CMD_SNP_CONFIG, &config, &argp->error); } static int sev_ioctl_do_snp_vlek_load(struct sev_issue_cmd *argp, bool writable) -- 2.54.0