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

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.