Re: [PATCH v3 2/6] x86/entry_64: Add VERW just before userspace transition

[Dave Hansen]

On 10/26/23 12:29, Pawan Gupta wrote:
> On Thu, Oct 26, 2023 at 07:25:27PM +0300, Nikolay Borisov wrote:
>> On 25.10.23 г. 23:52 ч., Pawan Gupta wrote:
>>> @@ -1520,6 +1530,7 @@ SYM_CODE_START(ignore_sysret)
>>>   	UNWIND_HINT_END_OF_STACK
>>>   	ENDBR
>>>   	mov	$-ENOSYS, %eax
>>> +	CLEAR_CPU_BUFFERS
>> nit: Just out of curiosity is it really needed in this case or it's doesn
>> for the sake of uniformity so that all ring3 transitions are indeed
>> covered??
> Interrupts returning to kernel don't clear the CPU buffers. I believe
> interrupts will be enabled here, and getting an interrupt here could
> leak the data that interrupt touched.

Specifically NMIs, right?

X86_EFLAGS_IF should be clear here.