lkml.org 
[lkml]   [2021]   [Feb]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 6/7] x86/boot/compressed/64: Check SEV encryption in 32-bit boot-path
From
Date
On 2/10/21 2:21 AM, Joerg Roedel wrote:
> + /* Store to memory and keep it in the registers */
> + movl %eax, rva(sev_check_data)(%ebp)
> + movl %ebx, rva(sev_check_data+4)(%ebp)
> +
> + /* Enable paging to see if encryption is active */
> + movl %cr0, %edx /* Backup %cr0 in %edx */
> + movl $(X86_CR0_PG | X86_CR0_PE), %ecx /* Enable Paging and Protected mode */
> + movl %ecx, %cr0
> +
> + cmpl %eax, rva(sev_check_data)(%ebp)
> + jne 3f
> + cmpl %ebx, rva(sev_check_data+4)(%ebp)
> + jne 3f

Also, I know that turning paging on is a *BIG* barrier. But, I didn't
think it has any effect on the caches.

I would expect that the underlying physical address of 'sev_check_data'
would change when paging gets enabled because paging sets the C bit.
So, how does the write of 'sev_check_data' get out of the caches and
into memory where it can be read back with the new physical address?

I think there's some bit of the SEV architecture that I'm missing.

\
 
 \ /
  Last update: 2021-02-10 17:49    [W:0.273 / U:0.004 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site