Re: [PATCH v5 1/7] x86/kexec: Consolidate relocate_kernel() function parameters

[Tom Lendacky <thomas.lendacky@amd.com>]

On 8/6/25 01:53, Huang, Kai wrote:
> On Tue, 2025-07-29 at 00:28 +1200, Kai Huang wrote:
>> During kexec, the kernel jumps to the new kernel in relocate_kernel(),
>> which is implemented in assembly and both 32-bit and 64-bit have their
>> own version.
>>
>> Currently, for both 32-bit and 64-bit, the last two parameters of the
>> relocate_kernel() are both 'unsigned int' but actually they only convey
>> a boolean, i.e., one bit information.  The 'unsigned int' has enough
>> space to carry two bits information therefore there's no need to pass
>> the two booleans in two separate 'unsigned int'.
>>
>> Consolidate the last two function parameters of relocate_kernel() into a
>> single 'unsigned int' and pass flags instead.
>>
>> Only consolidate the 64-bit version albeit the similar optimization can
>> be done for the 32-bit version too.  Don't bother changing the 32-bit
>> version while it is working (since assembly code change is required).
>>
>> Signed-off-by: Kai Huang <kai.huang@intel.com>
>> ---
>>
>>  v4 -> v5:
>>   - RELOC_KERNEL_HOST_MEM_ACTIVE -> RELOC_KERNEL_HOST_MEM_ENC_ACTIVE
>>     (Tom)
>>   - Add a comment to explain only RELOC_KERNEL_PRESERVE_CONTEXT is
>>     restored after jumping back from peer kernel for preserved_context
>>     kexec (pointed out by Tom).
>>   - Use testb instead of testq when comparing the flag with R11 to save
>>     3 bytes (Hpa).
>>
>>
> 
> Hi Tom,
> 
> Wondering do you have more comments?  Thanks.

Sorry for the delay, LGTM.

Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>