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[37.24.206.209]) by smtp.gmail.com with ESMTPSA id o20-20020a170906289400b00a4668980c12sm6046479ejd.182.2024.03.19.06.22.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 19 Mar 2024 06:22:11 -0700 (PDT) X-Outflank-Mailman: Message body and most headers restored to incoming version 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: b1fa7bb7-e5f3-11ee-afdd-a90da7624cb6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1710854531; x=1711459331; darn=lists.xenproject.org; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :references:cc:to:subject:from:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to; bh=iNHqaS4hCYlzXBeIJcF37JkLflryMYj84q8OtdKaqUc=; b=TLxRYrpLg2FVEDe/5B699AlyiAOFmsIdY3PCZoqTCQK3aD/FcDvzoTuOOtgA9B5tCF JB4mTUEMuPH1vzIIS+kItHVjKPFPsdtWet2zaSVG5n2q2Kd7oF39qlDHXfDw7PQFjuY2 who01+1rVCU609V4cyc6rkdd56N/w/pwTwW+ET6gDPZTdeT9wZxS8pH1JOp9EtUMT84X NxD+LMWtgJKdBx4zz9gsyeW7T3QXq8xx9Zs0T1LznPCkqtXyuYe7ovyTzTWnvKylTGPy aCADYjcOPuEY7GFcz8TenpTvUiyV/5IM7NdMJNTT87kB25p0OCoTpMQF3VhLm13or/v1 ZeGA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1710854531; x=1711459331; h=content-transfer-encoding:in-reply-to:autocrypt:content-language :references: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=iNHqaS4hCYlzXBeIJcF37JkLflryMYj84q8OtdKaqUc=; b=m0BBgbXkugHpdxlktv2tHPfGdidxsayFaq+qmCF+mJCUizW2fleA1JH3G/1KCyB137 XLeNKkf72IQofN8+6k9WpvR+zzxZDL0Cia2WgbyWWIVxED/wHBoAp8oDZ3w0yRxZtnPj tvPQULOSKpo8SZSeJjrfsIiq8WB1Ao2g4AOrGeVw27qBpe9n1J3wLrWfNpsSdTGD2JZH GsiViBYlipXUqVsMtvdRXQqE5vGcNpXy4wQJvZvHxkR+6PemKArGthc2defqK4OQdIOR tUfpYz2J+kye3FAfWV9OdaJ7hCqYQ0cf9OkUWjx5DuhcVypF2ywtJlfeusbCfKIpDF0o 4K0Q== X-Gm-Message-State: AOJu0YyEezz7J5EFzUPP6zcnlXvFG6qjWTAqfjQCgdJkfor1J89/QwSk bMCj9bBW9jp0Pwa1Rj246sGmW1lS8ojVxpL12fgLozA80Fs/8Ko6PGzaFI0s9SaCi4udIPh3dVw = X-Google-Smtp-Source: AGHT+IF5I93HlWa1k48yzQp5rLpOSD1GUXFpYyMPj6ExHw4qGKj5DTFa2ZHs6as+JVJ0AxG3nCOZ+A== X-Received: by 2002:a17:906:7b8f:b0:a46:50ca:b318 with SMTP id s15-20020a1709067b8f00b00a4650cab318mr11159149ejo.16.1710854531640; Tue, 19 Mar 2024 06:22:11 -0700 (PDT) Message-ID: <95699d2c-7e2a-40db-875f-907990797317@suse.com> Date: Tue, 19 Mar 2024 14:22:10 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird From: Jan Beulich Subject: [PATCH v5] x86/PoD: tie together P2M update and increment of entry count To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , Wei Liu , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , George Dunlap 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-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @suse.com) X-ZM-MESSAGEID: 1710854552129100001 Content-Type: text/plain; charset="utf-8" When not holding the PoD lock across the entire region covering P2M update and stats update, the entry count - if to be incorrect at all - should indicate too large a value in preference to a too small one, to avoid functions bailing early when they find the count is zero. However, instead of moving the increment ahead (and adjust back upon failure), extend the PoD-locked region. Fixes: 99af3cd40b6e ("x86/mm: Rework locking in the PoD layer") Signed-off-by: Jan Beulich Reviewed-by: George Dunlap --- v5: Re-arrange conditionals to have just a single unlock. v4: Shrink locked region a little again, where possible. v3: Extend locked region instead. Add Fixes: tag. v2: Add comments. --- a/xen/arch/x86/mm/p2m-pod.c +++ b/xen/arch/x86/mm/p2m-pod.c @@ -1348,19 +1348,28 @@ mark_populate_on_demand(struct domain *d } } =20 + /* + * P2M update and stats increment need to collectively be under PoD lo= ck, + * to prevent code elsewhere observing PoD entry count being zero desp= ite + * there actually still being PoD entries (created by the p2m_set_entr= y() + * invocation below). + */ + pod_lock(p2m); + /* Now, actually do the two-way mapping */ rc =3D p2m_set_entry(p2m, gfn, INVALID_MFN, order, p2m_populate_on_demand, p2m->default_access); if ( rc =3D=3D 0 ) { - pod_lock(p2m); p2m->pod.entry_count +=3D 1UL << order; p2m->pod.entry_count -=3D pod_count; BUG_ON(p2m->pod.entry_count < 0); - pod_unlock(p2m); + } + + pod_unlock(p2m); =20 + if ( rc =3D=3D 0 ) ioreq_request_mapcache_invalidate(d); - } else if ( order ) { /*