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[142.79.211.230]) by smtp.gmail.com with ESMTPSA id f9sm3160208otq.27.2021.05.17.06.48.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 17 May 2021 06:48:32 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 4dee4ff9-b37a-4522-9bc7-e0050e95dbf0 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=Y7G3TzUfMF26NrwSfO4KjIdPwYhYispCIDNJBE6rnKU=; b=IlUjmEUztnRpvBfIDXO7inyXDXdMskWLTvaqVIFQNg/sz7Sm85rGV+V/NycCnzCMqp pR41oIEn6xzSWBDCE66TpcjX6qvaIxxkpGkrsNqRDG6fpqnsu2OSG8vTPdzkJ4UQcAmF vCk4Og0AUaXC+Rx6Tycg1z1yITNJBeGIVh+EKO+wJpyfqne9xBYo6GBQVfvgLU03xVpB qHvIQ3dwr+nVtRMdn4xrH2UGRqgIu9jxk4ditSoGxHEyIiEN7hQeODI70v97xH6/mTw3 0h3rOWsJ0JiedFQaXs1hiDZDR4l0+g8RR+/wHKjxHwaBPWEc0DGLcB9//Ng8jc9U+/9E a5MQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=Y7G3TzUfMF26NrwSfO4KjIdPwYhYispCIDNJBE6rnKU=; b=cykTW77MJ5VJkYKe1cV4X9tA2x315TtUCDAPjL1EW8j2oevI0ke+5/t2ia3/dqzkII gJ67YAwop4j/UHsookWxELSG8nkNV8Q/FFo3ZoWQXSo9QYxttAXsLucMkIEJLxin5Ftt hm3u7c58O28Tgw/OjOlgsGe2mbYIfYZSTejk1gkDcXWfx42Udr6HFN78iL1QESpQyHg3 kv3j4MlGmgulg6iuiJEoS0fhaxsng++U/ZLBIt6Q2Eq6599wxQGzuEZYF+U8VR2bZ1Hy jKZoLHph21xIFp51G/MqW0DjL+qZVsaJ9NDrivdDQnEc/QYGfJJVRzT1dqOqN6cE8Lmn B0ww== X-Gm-Message-State: AOAM531A6cT3f87ypcbOazVlEBumT5KxlGKvn8uyjLgzHOF0yhCrnI7p t11WQd9ByhsnT2JhqC38ykU= X-Google-Smtp-Source: ABdhPJyLzO83i4D+oIyg6HoPQKkQpEgGaCBeACLMXfFi8Xmghwtvoqj4t3iSgcq4bojWvN+4i7BQhA== X-Received: by 2002:a9d:a14:: with SMTP id 20mr45335812otg.86.1621259312975; Mon, 17 May 2021 06:48:32 -0700 (PDT) Subject: Re: [PATCH v2 1/4] usb: early: Avoid using DbC if already enabled To: Jan Beulich Cc: Jann Horn , Lee Jones , Chunfeng Yun , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, Greg Kroah-Hartman References: <8ccce25a-e3ca-cb30-f6a3-f9243a85a49b@suse.com> From: Connor Davis Message-ID: <16400ee4-4406-8b26-10c0-a423b2b1fed0@gmail.com> Date: Mon, 17 May 2021 07:48:52 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.10.1 MIME-Version: 1.0 In-Reply-To: <8ccce25a-e3ca-cb30-f6a3-f9243a85a49b@suse.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US On 5/17/21 3:32 AM, Jan Beulich wrote: > On 14.05.2021 02:56, Connor Davis wrote: >> Check if the debug capability is enabled in early_xdbc_parse_parameter, >> and if it is, return with an error. This avoids collisions with whatever >> enabled the DbC prior to linux starting. > Doesn't this go too far and prevent use even if firmware (perhaps > mistakenly) left it enabled? > > Jan Yes, but how is one supposed to distinguish the broken firmware and non-broken firmware cases? > >> Signed-off-by: Connor Davis >> --- >> drivers/usb/early/xhci-dbc.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/drivers/usb/early/xhci-dbc.c b/drivers/usb/early/xhci-dbc.c >> index be4ecbabdd58..ca67fddc2d36 100644 >> --- a/drivers/usb/early/xhci-dbc.c >> +++ b/drivers/usb/early/xhci-dbc.c >> @@ -642,6 +642,16 @@ int __init early_xdbc_parse_parameter(char *s) >> } >> xdbc.xdbc_reg = (struct xdbc_regs __iomem *)(xdbc.xhci_base + offset); >> >> + if (readl(&xdbc.xdbc_reg->control) & CTRL_DBC_ENABLE) { >> + pr_notice("xhci debug capability already in use\n"); >> + early_iounmap(xdbc.xhci_base, xdbc.xhci_length); >> + xdbc.xdbc_reg = NULL; >> + xdbc.xhci_base = NULL; >> + xdbc.xhci_length = 0; >> + >> + return -ENODEV; >> + } >> + >> return 0; >> } >> >> Thanks, Connor