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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a6f56f4182fsm149764266b.178.2024.06.13.23.27.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 Jun 2024 23:27:12 -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: 231680b7-2a17-11ef-b4bb-af5377834399 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1718346433; x=1718951233; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=uiiGIfn0KxmgRHe7E3PFtjPcK8iBnXHQ2pGIajwaFEM=; b=X+A5G9OIM8BpvhT9gsN3o07R5tHO3DoOUOhnlQVog+x3Xw51sqi2kW1+iuaKF445xJ 1s0WqaoEfsIks3Hma9iPxzJqJmkux60/HgQ5ve4HBb1ww+aaS1P9YWCsaL8rBjJFON+v AJdwV0sIjXaEwD/3yAmDgEwj+ZcwpMpkWtuj9Lm8dHS6CG1AUYeBJyWpK33sAVIGXBe/ RHLDuqcJb1Av0/T9CD7VyLGs8wH1Qe/r0VXJ6c4JC2AHH82LZEqg+OK6cTIH8dNhmsam RDxmfI+AFu9JaZYhfhekAvRiMH34Kx3N07CccJZEGWhaEbpsqqAfjUpe0rUz1UTCuvBC MMXQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1718346433; x=1718951233; h=content-transfer-encoding:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=uiiGIfn0KxmgRHe7E3PFtjPcK8iBnXHQ2pGIajwaFEM=; b=Bx1dX1uFRdmRsqbz6tnq9mFaHy+7IohSSqM/hAjkxhgYPvm20ppPxnlC0Wr3lL9Vcf Tr4yuizbR8f4UQI0hSBU8H0swXF5NTEsuz8/TdFyXTDYxs9jJLIlrWpOlkXFG84WZ9yk EibJyv9za/y/J8ztlFUDNc3ifFfpAR4fOnskE92iNniKYWx8FaQH3Az1+36XZZLF3M+R hk/BxhryAk3a0n9eM3X47zEUG1h8j26mKhfSxY1qvslIfuzHiAWkEvgwHAdvCocf9rgx VV9H7tvQ5glmcZXto5MqKTnyvPWEJ+ePxIWnI2IQSeXPjAU2eCtH8NQnUSULnvKbMRmX LFqA== X-Forwarded-Encrypted: i=1; AJvYcCXwtQY0WSZdoR1Mh3kwPx6z5y3ngEBnbLvoLjSBgQc4ukws5CifKRK1wgvKyJLSFPtEX01Daa+rDHqetDcLsbR7ODhfLdiECQUQHrlCgVk= X-Gm-Message-State: AOJu0YxCnlCKRA6C29Dn0C3Q5VfkbJ6Qo6oyazPSFbHf/flfhk3cfG4S DaNnfJaF+R3owkkePERN/+dmtJx6dPeVWFj5pbab6ZynIa35HamCY5mbcGk1EQ== X-Google-Smtp-Source: AGHT+IEZzlIwqPD90GoYGlKcMjMkKB1HtzNzQyksXMZRCRVxkORVHCCs11PdOI/z3vVWVoT153OX6g== X-Received: by 2002:a17:906:388b:b0:a6f:1475:33a8 with SMTP id a640c23a62f3a-a6f60d29606mr105070866b.17.1718346432789; Thu, 13 Jun 2024 23:27:12 -0700 (PDT) Message-ID: Date: Fri, 14 Jun 2024 08:27:11 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH for 4.19?] x86/Intel: unlock CPUID earlier for the BSP To: Andrew Cooper Cc: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Oleksii Kurochko , "xen-devel@lists.xenproject.org" References: <82277592-ea96-47c8-a991-7afd97d7a7bc@suse.com> Content-Language: en-US From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 13.06.2024 18:17, Andrew Cooper wrote: > On 13/06/2024 9:19 am, Jan Beulich wrote: >> Intel CPUs have a MSR bit to limit CPUID enumeration to leaf two. If >> this bit is set by the BIOS then CPUID evaluation does not work when >> data from any leaf greater than two is needed; early_cpu_init() in >> particular wants to collect leaf 7 data. >> >> Cure this by unlocking CPUID right before evaluating anything which >> depends on the maximum CPUID leaf being greater than two. >> >> Inspired by (and description cloned from) Linux commit 0c2f6d04619e >> ("x86/topology/intel: Unlock CPUID before evaluating anything"). >> >> Signed-off-by: Jan Beulich >> --- >> While I couldn't spot anything, it kind of feels as if I'm overlooking >> further places where we might be inspecting in particular leaf 7 yet >> earlier. >> >> No Fixes: tag(s), as imo it would be too many that would want >> enumerating. > > I also saw that go by, but concluded that Xen doesn't need it, hence why > I left it alone. > > The truth is that only the BSP needs it.  APs sort it out in the > trampoline via trampoline_misc_enable_off, because they need to clear > XD_DISABLE in prior to enabling paging, so we should be taking it out of > early_init_intel(). Except for the (odd) case also mentioned to Roger, where the BSP might have the bit clear but some (or all) AP(s) have it set. > But, we don't have an early BSP-only early hook, and I'm not overwhelmed > at the idea of exporting it from intel.c > > I was intending to leave it alone until I can burn this whole > infrastructure to the ground and make it work nicely with policies, but > that's not a job for this point in the release... This last part reads like the rest of your reply isn't an objection to me putting this in with Roger's R-b, but it would be nice if you could confirm this understanding of mine. Without this last part it, especially the 2nd from last paragraph, certainly reads a little like an objection. Jan