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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id p13-20020a05600c204d00b00410df4bf22esm1453519wmg.38.2024.02.14.02.12.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 14 Feb 2024 02:12:28 -0800 (PST) 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: 8f7b5a7c-cb21-11ee-98f5-efadbce2ee36 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1707905549; x=1708510349; darn=lists.xenproject.org; h=content-transfer-encoding:autocrypt:content-language:cc:to:subject :from:user-agent:mime-version:date:message-id:from:to:cc:subject :date:message-id:reply-to; bh=Pnu4VXy5X8iZt6vvrCxKxi+hnaJLFi62JTayobfCEu0=; b=I5JKJyd4eEgh2DkRqvO9Rurzvp4PuY403IiVanUFTHTnrZOaRGEWVMQ1Llc1KtD+F3 iF309RF5QxtagorDftdhzyNJXDbLT6fselTbniky33aJ1i/Hi5SYEz3QasPBfSBhtdIL iD4al0pyFV48udaHJxM8v75yMqRtiLx6ZZiGK1EQ7sbvhU2iCxz/bdhO2S97tcOVdSqh M30DSb4LCcU+4vsVTnnCsxPA4jvxH7D2CEioioX5oU09HiUqRnyJU6QhR53zNKjRD/hG TUkVnGvzaDKdq7KTbUaVMSGKwBZUB8tDmnVDustmxwur5I3sOqVOETI7BLtFlA+iSMmG Gz5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1707905549; x=1708510349; h=content-transfer-encoding:autocrypt:content-language:cc:to:subject :from:user-agent:mime-version:date:message-id:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=Pnu4VXy5X8iZt6vvrCxKxi+hnaJLFi62JTayobfCEu0=; b=AZHyecZKruWNxJpHWXpO++5IINejiicd3qg6dEbHEA8aBeF+zk/kphrHsH1fkNsSye aYFz3TLA1IgC/jW7hwFluCClTpgomwZZOoIdak7o40dCFUMmKnbVPtRCOvXElMLnddy1 dw4QOZgaji89Zn4MGe/D/FRXqcCahC07t0pPL8brPdpc0VKg5LZf4UQtnDSzuK4nZ2kU dCyMw4heAn5N8cmKUjMs38T0V7cWO/z2MyHQhJYlF/oyTaZ4GmVa/4P5EQ8CT75fH5bN GIhcuGc+h44Nxya0OX9J8v9G5EQ6T1DoTZdf8F6NxavXj6zVefyoGRLsD1qo67T+BYHT yX5Q== X-Gm-Message-State: AOJu0YzVaM+aTeckJMzRVkeAe3j86hZNtllhKgnhaZF9Z3faDRqJNy+o /vp4c8Jck48ZDGABxgaTQ8K/XuqW5vKi+FJ5Nr79ScoMJpbKlGvHPZmYWYRWcuKowd35dODIWDA = X-Google-Smtp-Source: AGHT+IG3QnsVOHp4kjee9gR7OshWqgfwQNgC1rLlP678YEJa158UljafE+ez5qWAho9mMNWzhZ0gjQ== X-Received: by 2002:a05:6512:234f:b0:511:a90b:5334 with SMTP id p15-20020a056512234f00b00511a90b5334mr986271lfu.20.1707905549268; Wed, 14 Feb 2024 02:12:29 -0800 (PST) Message-ID: <79ed633d-b0bd-4a7d-a0c6-37a034e1ee96@suse.com> Date: Wed, 14 Feb 2024 11:12:28 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Jan Beulich Subject: [PATCH v2] Argo: don't obtain excess page references To: "xen-devel@lists.xenproject.org" Cc: Christopher Clark , Andrew Cooper , George Dunlap , Julien Grall , Stefano Stabellini , Wei Liu 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 find_ring_mfn() already holds a page reference when trying to obtain a writable type reference. We shouldn't make assumptions on the general reference count limit being effectively "infinity". Obtain merely a type ref, re-using the general ref by only dropping the previously acquired one in the case of an error. Signed-off-by: Jan Beulich Reviewed-by: Julien Grall --- I further question the log-dirty check there: The present P2M type of a page doesn't really matter for writing to the page (plus it's stale by the time it is looked at). Instead I think every write to such a page needs to be accompanied by a call to paging_mark_dirty(). --- v2: Re-base. --- a/xen/common/argo.c +++ b/xen/common/argo.c @@ -1426,7 +1426,7 @@ find_ring_mfn(struct domain *d, gfn_t gf switch ( p2mt ) { case p2m_ram_rw: - if ( !get_page_and_type(page, d, PGT_writable_page) ) + if ( !get_page_type(page, PGT_writable_page) ) ret = -EINVAL; break; @@ -1441,7 +1441,8 @@ find_ring_mfn(struct domain *d, gfn_t gf break; } - put_page(page); + if ( unlikely(ret) ) + put_page(page); return ret; }