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AJvYcCUaYT/Kct0pHyzrW757fIV54UMDOq3tncCe7cU2lT32n18EMEIJnyVhjiXTSt/Ptp+8WAD8S4ftbp8=@lists.xenproject.org X-Gm-Message-State: AOJu0Yy9uDWUZr4luXWdnTf2iwzde6Mb0sFbvi6b4gScOh8HMW1I9kTc uNGT9xgDttn1zBpCHdO3VC6kiAJj3/4peQrBWw8P4lb9GJXc93WzlgpehzYxKQ== X-Google-Smtp-Source: AGHT+IEUI4NSEkGO+6SsmB2bVAPJV0pkEawMS79wssmcY3Eaiv48fMiaTGfPLVgAJtuQ1qj/bsD4Ow== X-Received: by 2002:a05:6512:3c87:b0:53d:a2cb:349e with SMTP id 2adb3069b0e04-53dab291a9amr4294289e87.4.1731915925866; Sun, 17 Nov 2024 23:45:25 -0800 (PST) Message-ID: Date: Mon, 18 Nov 2024 08:45:24 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/3] x86/ucode: Fix cache handling in microcode_update_helper() To: Andrew Cooper Cc: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , Stefano Stabellini , Xen-devel References: <20241112211915.1473121-1-andrew.cooper3@citrix.com> <20241112211915.1473121-3-andrew.cooper3@citrix.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: 7bit On 15.11.2024 19:03, Andrew Cooper wrote: > On 14/11/2024 11:26 am, Jan Beulich wrote: >> On 12.11.2024 22:19, Andrew Cooper wrote: >>> microcode_update_cache() now has a single caller, but inlining it shows how >>> unnecessarily complicated the logic really is. >>> >>> Outside of error paths, there is always one microcode patch to free. Its >>> either result of parse_blob(), or it's the old cached value. >>> >>> In order to fix this, have a local patch pointer (mostly to avoid the >>> unnecessary verbosity of patch_with_flags.patch), and always free it at the >>> end. The only error path needing care is the IS_ERR(patch) path, which is >>> easy enough to handle. >>> >>> Also, widen the scope of result. We only need to call compare_patch() once, >>> and the answer is still good later when updating the cache. In order to >>> update the cache, simply SWAP() the patch and the cache pointers, allowing the >>> singular xfree() at the end to cover both cases. >>> >>> This also removes all callers microcode_free_patch() which fixes the need to >>> cast away const to allow it to compile. >> I'm sure you're well aware that this in turn is just because of your opposition >> to xfree() and alike taking const void *. > > My opposition, and the C standards committee, and MISRA to name but a few. The C standard's committee - yes, if we mean to stick to free()'s properties to the letter (I don't think they have any idea about unmap-like things). For Misra though, would you mind educating me where they would have a concern? Jan