Re: [PATCH v5 00/25] context_tracking,x86: Defer some IPIs until a user->kernel transition

[Dave Hansen]

On 5/2/25 02:55, Valentin Schneider wrote:
> My gripe with that was having two separate mechanisms
> - super early entry around SWITCH_TO_KERNEL_CR3)
> - later entry at context tracking

What do you mean by "later entry"?

All of the paths to enter the kernel from userspace have some
SWITCH_TO_KERNEL_CR3 variant. If they didn't, the userspace that they
entered from could have attacked the kernel with Meltdown.

I'm theorizing that if this is _just_ about avoiding TLB flush IPIs that
you can get away with a single mechanism.