[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [PATCH 5/5] x86/ucode: Drop the match_reg[] field from AMD's microcode_patch
- To: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
- From: Jan Beulich <jbeulich@xxxxxxxx>
- Date: Wed, 26 Feb 2025 08:18:34 +0100
- Autocrypt: addr=jbeulich@xxxxxxxx; 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
- Cc: Roger Pau Monné <roger.pau@xxxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Wed, 26 Feb 2025 07:19:03 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 25.02.2025 23:01, Andrew Cooper wrote:
> On 28/10/2024 1:18 pm, Jan Beulich wrote:
>> On 24.10.2024 15:22, Andrew Cooper wrote:
>>> This was true in the K10 days, but even back then the match registers were
>>> really payload data rather than header data.
>>>
>>> But, it's really model specific data, and these days typically part of the
>>> signature, so is random data for all intents and purposes.
>>>
>>> No functional change.
>>>
>>> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>> ---
>>> CC: Jan Beulich <JBeulich@xxxxxxxx>
>>> CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
>>>
>>> The single difference from this is:
>>>
>>> @@ -207587,7 +207587,7 @@
>>> ffff82d0402ad261: 4c 89 ce mov %r9,%rsi
>>> ffff82d0402ad264: 4c 39 c8 cmp %r9,%rax
>>> ffff82d0402ad267: 0f 82 c2 11 f6 ff jb ffff82d04020e42f
>>> <amd_ucode_parse.cold+0x55>
>>> -ffff82d0402ad26d: 41 83 f9 3f cmp $0x3f,%r9d
>>> +ffff82d0402ad26d: 41 83 f9 1f cmp $0x1f,%r9d
>>> ffff82d0402ad271: 0f 86 b8 11 f6 ff jbe ffff82d04020e42f
>>> <amd_ucode_parse.cold+0x55>
>>> ffff82d0402ad277: 85 ed test %ebp,%ebp
>>> ffff82d0402ad279: 75 55 jne ffff82d0402ad2d0
>>> <amd_ucode_parse+0x170>
>>>
>>> which is "mc->len < sizeof(struct microcode_patch)" expression in
>>> amd_ucode_parse().
>> Yet is it correct to effectively relax that check, i.e. to accept something
>> we previously would have rejected?
>
> Yes. This is the bounds check about whether it's safe to look at fields
> in the header. It's not part of the other validity checks.
Hmm, okay:
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
Jan
|
