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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id u7-20020a17090626c700b00a46e56b181bsm1799100ejc.4.2024.03.20.08.09.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 20 Mar 2024 08:09:34 -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: dce8ffa3-e6cb-11ee-afdd-a90da7624cb6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1710947375; x=1711552175; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:from:references:cc :to:content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=5fWkWPnMdhkSD8eYem4ijP7X1u7JNbqBHCtvSL7Uxeo=; b=VKS9PFvLCBrkQhsikGJZKJQMj6VgAZFmOOLU22PMeRVRvEIrLQTN4rssBBnk7rlP5R X4rcYo0CORP51nFVuEqD5n2q2cO3ZtdflnIZNiLZMxizGlihDBr3/StO+LqYP/AvmIiq cOPT5j6kLruvsQRS6Y7U2PiE2QPwlxefm0rb/HOU3BaRGei4YMNoWem0mLtM5eUI+AKn 6qwMYMXd2jHXlUDS806bGN1zjHeOqrKlm6p5AxRc/+nN4krBx+n/1IA5Vgx0ZOgfLSwY 8w9ylsTRiUHwOVNzypOXCgiKFzPmNJnzs3KArXkq7vs0MPZ2gNLAA6sAh5oSKRaWRiqZ y+cg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1710947375; x=1711552175; h=content-transfer-encoding:in-reply-to:autocrypt:from:references:cc :to:content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=5fWkWPnMdhkSD8eYem4ijP7X1u7JNbqBHCtvSL7Uxeo=; b=uRAobbsZBJmJ9VauA5hrskkLh1r2I0fhP7/inwxzV9WeA46WnNLf6D839sTU5pcIfj LmwYqoqpPgAs8liE2eFjrCmd+2d+JnDRl+lXu4YPNV5HiOiEZoEybslQG54FUqRraUvw 4sNda7c78cs7FDBt5vEMskdPi+C/una+hclPUse3nCQAlX6oyvnzJ7nmYobY3giVqE5A PnEJ6B/vt/R0XTgFulq5Zx7TJqLfMtERLAT2tgjtadxtZskvu1e3cwHLUjez5IirIxkH rtFOZ+V4cRbnlUD7XllEeAYj9KOab5acipsDCsduzrcjemNF4tZYs/nkOsd0ngv6G0nW JV9A== X-Forwarded-Encrypted: i=1; AJvYcCUg43n0UVR7OrFV4sMLkSzHvOTAtnXVCbcPyzh7Lh/MHDvQ24FlZf74aQWhaJMt4GlBT7SdEuZhA2CE1K/+J16PTosUt7PeJcoh2GFuQY0= X-Gm-Message-State: AOJu0YyCE7MeSD29/a53tLBtcZjWpL0CAx47j2HwpV4H2Pn5z5s+iWEe Q+JiEEIKbtePFt11AZBJJJicCCo7zbXCkh/0kBKePTs11O3hsGpcJBY9hRXdnA== X-Google-Smtp-Source: AGHT+IF6AdUYewFCcc9PdxDShniczEzSSWIGGS8subtQtPMt8KhqvrhhM8q4+/K9xVvLQqJwemNaJg== X-Received: by 2002:a17:906:124b:b0:a46:8846:5aa0 with SMTP id u11-20020a170906124b00b00a4688465aa0mr4536995eja.56.1710947374911; Wed, 20 Mar 2024 08:09:34 -0700 (PDT) Message-ID: <73314dc5-0145-4aa7-a3cd-23c943235392@suse.com> Date: Wed, 20 Mar 2024 16:09:33 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] x86/vcpu: relax VCPUOP_initialise restriction for non-PV vCPUs Content-Language: en-US To: Roger Pau Monne Cc: Andrew Cooper , George Dunlap , Julien Grall , Stefano Stabellini , Wei Liu , xen-devel@lists.xenproject.org References: <20240320135720.68894-1-roger.pau@citrix.com> 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: <20240320135720.68894-1-roger.pau@citrix.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 20.03.2024 14:57, Roger Pau Monne wrote: > There's no reason to force HVM guests to have a valid vcpu_info area when > initializing a vCPU, as the vCPU can also be brought online using the local > APIC, and on that path there's no requirement for vcpu_info to be setup ahead > of the bring up. Note an HVM vCPU can operate normally without making use of > vcpu_info. While I'd agree if you started with "There's no real need to force ...", I still think there is a reason: If one wants to use paravirt interfaces (i.e. hypercalls), they would better do so consistently. After all there's also no need to use VCPUOP_initialise, yet you're not disabling its use. As said in reply to Andrew's reply, besides acting as a sentinel that structure instance also acts as a sink for Xen accesses to a vCPU's vcpu_info. By removing the check, you switch that from being a safeguard to being something that actually has to be expected to be accessed. Unless you've audited all uses to prove that no such access exists. Jan