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X-CSE-ConnectionGUID: Zw/PadVpSvuh8n2s6I6GEw== X-CSE-MsgGUID: GFn5tleGRb6WsCUz0kEpSg== X-IronPort-AV: E=McAfee;i="6800,10657,11902"; a="88568323" X-IronPort-AV: E=Sophos;i="6.27,97,1787036400"; d="scan'208";a="88568323" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Sep 2026 13:25:45 -0700 X-CSE-ConnectionGUID: mzHLDUlsQY6c3yGYli/YWA== X-CSE-MsgGUID: n3KA9XEoRL2PCqJdXkYAgg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,97,1787036400"; d="scan'208";a="269409116" Received: from smithj1-mobl2.amr.corp.intel.com (HELO [10.125.108.26]) ([10.125.108.26]) by fmviesa008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Sep 2026 13:25:44 -0700 Message-ID: <0aee9055-9cfb-4047-8fdf-024964d123d1@intel.com> Date: Fri, 11 Sep 2026 13:25:43 -0700 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] x86/early_printk: Avoid #VE emulation for TDX guest serial output To: Vishal Verma , x86@kernel.org, Dave Hansen , Kiryl Shutsemau , Rick Edgecombe Cc: linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org References: <20260910-b4-tdx_earlyprintk_tdcalls-v1-0-4b2b1bf9001b@intel.com> <20260910-b4-tdx_earlyprintk_tdcalls-v1-2-4b2b1bf9001b@intel.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 9/10/26 15:34, Vishal Verma wrote: > +/* Substitute the hypercall accessors, but only in an actual TDX guest */ > +static __init void early_serial_tdx_init(void) > +{ > + if (!cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) > + return; > + > + static_call_update(serial_in, tdx_serial_in); > + static_call_update(serial_out, tdx_serial_out); > +} > +#else > +static inline void early_serial_tdx_init(void) { } > +#endif /* CONFIG_INTEL_TDX_GUEST */ > + > static int early_serial_putc(unsigned char ch) > { > unsigned timeout = 0xffff; > @@ -160,6 +204,9 @@ static __init void early_serial_init(char *s) > unsigned long baud = DEFAULT_BAUD; > char *e; > > + /* Must be before early_serial_hw_init(), which does port I/O */ > + early_serial_tdx_init(); I really don't like the idea of putting any code in here. How about just adding a case to setup_early_printk(). Perhaps: #ifdef CONFIG_TDX_GUEST if (!strncmp(buf, "tdx", 3)) { early_serial_tdx_init(); early_serial_init(buf + 3); early_console_register(&early_serial_console, keep); } #endif Then folks can just use earlyprintk=tdx.