On 9/13/21 9:14 AM, Joerg Roedel wrote:
On Mon, Sep 13, 2021 at 09:02:38AM -0700, Dave Hansen wrote:
quoted
On 9/13/21 8:55 AM, Joerg Roedel wrote:
quoted
This does not work under SEV-ES, because the hypervisor has no access
to the vCPU registers and can't make modifications to them. So an
SEV-ES guest needs to reset the vCPU itself and park it using the
AP-reset-hold protocol. Upon wakeup the guest needs to jump to
real-mode and to the reset-vector configured in the AP-Jump-Table.
How does this end up looking to an end user that tries to kexec() from a
an SEV-ES kernel? Does it just hang?
Yes, the kexec will just hang. This patch-set contains code to disable
the kexec syscalls in situations where it would not work for that
reason.
Got it. The end-user-visible symptom just wasn't obvious. If you
revise these, it might be nice to add that so that folks who cherry-pick
stable patches or update to new stable kernels have an idea what this
might fix.