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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-39ab907da9asm16933532f8f.90.2025.03.27.02.30.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 27 Mar 2025 02:30:06 -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: 1245ab17-0aee-11f0-9ffa-bf95429c2676 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1743067807; x=1743672607; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :references:cc:to:from:subject:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to; bh=W4vZBvYaByNd9A1fE5NNYaUZh1Or1PdoNuWSV/1koD0=; b=DUdK0Y7NUurY44iImp8JNB9IG9J+MPTATQ2DqQj2cqiOIl/phjvGDrATaIBtE+DpJS C5al0EFOhkWQeAwP08m2DJG6sZeUAdJbJDh8Vf8z8WMjqdqupPRyV2e/j73P/XwL8aUK AMz9K2WQ8qCA5Ga5IF3JvzI4oqH9wIpzUc+v5RxHrRGc8CfWYGJqfuCJwS9mC9v1HaTb B+G77gvi00hmSjG6se72PbMxLLsplsfTnnZEFSFZUP/n/hOE9Ns7gNelqK7GG2L7r04G a4YcqO7zyk3KGVjIVgcAdVwpopuYfmGt4xa32EZBPLw/wK2aBZMsKEdIkhAufT9DhyyP k3AQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1743067807; x=1743672607; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :references:cc:to:from:subject:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=W4vZBvYaByNd9A1fE5NNYaUZh1Or1PdoNuWSV/1koD0=; b=sCSkCjZIP9UA44UVsOlF7RzNSGLkmTOysVTQvonMmYNJES7AwQFe046TNZq6fBllDA jJMv/EX25tXdEFokC8U2Rit4cRAzm7nRWuOlor7MthId+oTYb3jWXRgCaRda1EaJfe3V mQnkuqCmd0jL7nfUcuH9hfmo4GJrbeDT7tjfN7qdzLjzOPZA6McMXhHArYnap8Uq993L CpoRON8M5uxCc+cwRUCRYDhH7/pnKOlnhfyeuzc6LGYt91pbY+jsFThKpGhkCr3MxQtU kwjusnni7m1u0ac+cSNzDAt8qU/F+UTAbRGhvEbWNY9uePa0am0ekEe6T1Wcjg1SBfpI D4bQ== X-Gm-Message-State: AOJu0Yx12D5LxLBwXDGrRw2sYmhRUAH1EvuR1Iq7q5NFafLdAuPivVlv NhJv+tA2nY8qfsGChfRZ1sQ4EBbnvFFQpJ04BfHJWNmpZW4HWQSN28ObdfNERw== X-Gm-Gg: ASbGncuN605M8xGhQ6eg4tpSofrH9s6FCPrgQz1sqTeX6nz3oZJSQlqJTeFRi9vtUv5 37H0LZf3ZNHlJFLXbYZDqgc9cFD+8m2EGktdZZEh6i2HMZ5xMuz44pkuXaHBfk42hwSiXiIjxca Lw8CMv/WuL8Aj7bBAE7sV76ODSD4U6ahs8t75+bhFxUa9a3eV8xJMzpvUImL+MRw4CHWIOT/cBi 2b8HCwg5IfeuQYttVn94PsH3UVEBLJfYiq8bGmvriHjhW4Yo4jhcQk45hmrAFGPUFeyuHQXv/N/ PMVc/ysvzSI8I1uEi6g85BnG+cKl5j/weIvq0Y1nt1PDKKfK/PVGY3NBu+6inaoseasNLSkNReF wkaawirvH9Ta22wdVJE41+YGXdkfi9Q== X-Google-Smtp-Source: AGHT+IExw33n57Jurm/4GA5OUknOZplGOJ7D9HQh3OoC5LzEXuN2WqDGWeMjvojVRDkPsLDwleIXDw== X-Received: by 2002:a05:6000:4011:b0:38d:bccf:f342 with SMTP id ffacd0b85a97d-39ad1760510mr2298061f8f.43.1743067806845; Thu, 27 Mar 2025 02:30:06 -0700 (PDT) Message-ID: Date: Thu, 27 Mar 2025 10:30:05 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/CPU: don't hard-code MTRR availability From: Jan Beulich To: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= Cc: "xen-devel@lists.xenproject.org" , Andrew Cooper References: Content-Language: en-US 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 27.03.2025 10:15, Jan Beulich wrote: > On 27.03.2025 09:21, Roger Pau Monné wrote: >> My main concern is whether the !mtrr path is still functional. Have >> you tried booting the resulting hypervisor with MTRR masked on CPUID? >> >> (or alternatively short-circuiting cpu_has_mtrr == 0?) > > I didn't think this would be a prereq here. If we boot in an environment truly > lacking MTRR, we'll crash on the first MTRR MSR access - none of those accesses > use the safe accessors. Since you asked, I tried booting with "cpuid=no-mtrr". > As I'm doing this on a system with console, all I can say is that it takes > minutes to reach the point where we'd start setting up Dom0 (which itself then > takes so long that I timed out waiting for it to make progress), due to all > screen output becoming unbelievably slow after AP bringup. Surely something's > screwed somewhere, as VRAM accesses being slow (or fast) shouldn't depend on AP > bringup having completed. I actually suspect it's not just VRAM accesses which > are slow, but that we're left running in uncachable mode altogether for whatever > reason. I think found a trivial way to avoid this, and the change there imo makes sense even if I can't explain this particular aspect of it. I'll submit that independently. Jan