On 02/02/21 20:01, Michael Roth wrote:
Hi Sean, Paolo,
Following up from previous v3 discussion:
https://lore.kernel.org/kvm/X%2FSfw15OWarseivB@xxxxxxxxxx/
I got bit in internal testing by a bug in v3 of this series that Sean had
already pointed out in v3 comments, so I thought it might be good to go
ahead and send a v4 with those fixes included. I also saw that Sean's vmsave
helpers are now in kvm/queue, so I've rebased these on top of those, and
made use of the new vmsave/vmload helpers:
https://lore.kernel.org/kvm/8880fedc-14aa-1f14-b87b-118ebe0932a2@xxxxxxxxxx/
Thanks!
-Mike
= Overview =
This series re-works the SVM KVM implementation to use vmload/vmsave to
handle saving/restoring additional host MSRs rather than explicit MSR
read/writes, resulting in a significant performance improvement for some
specific workloads and simplifying some of the save/load code (PATCH 1).
With those changes some commonalities emerge between SEV-ES and normal
vcpu_load/vcpu_put paths, which we then take advantage of to share more code,
as well as refactor them in a way that more closely aligns with the VMX
implementation (PATCH 2 and 3).
Queued, thanks.
Paolo
v4:
- rebased on kvm/queue
- use sme_page_pa() when accessing save area (Sean)
- make sure vmload during host reboot is handled (Sean)
- introduce vmload() helper like we have with vmsave(), use that instead
of moving the introduce to ASM (Sean)
v3:
- rebased on kvm-next
- remove uneeded braces from host MSR save/load loops (Sean)
- use page_to_phys() in place of page_to_pfn() and shifting (Sean)
- use stack instead of struct field to cache host save area outside of
per-cpu storage, and pass as an argument to __svm_vcpu_run() to
handle the VMLOAD in ASM code rather than inlining ASM (Sean/Andy)
- remove now-uneeded index/sev_es_restored fields from
host_save_user_msrs list
- move host-saving/guest-loading of registers to prepare_guest_switch(),
and host-loading of registers to prepare_host_switch, for both normal
and sev-es paths (Sean)
v2:
- rebase on latest kvm/next
- move VMLOAD to just after vmexit so we can use it to handle all FS/GS
host state restoration and rather than relying on loadsegment() and
explicit write to MSR_GS_BASE (Andy)
- drop 'host' field from struct vcpu_svm since it is no longer needed
for storing FS/GS/LDT state (Andy)
arch/x86/kvm/svm/sev.c | 30 +-----------------------------
arch/x86/kvm/svm/svm.c | 107 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++---------------------------------------------------
arch/x86/kvm/svm/svm.h | 29 +++++------------------------
arch/x86/kvm/svm/svm_ops.h | 5 +++++
4 files changed, 67 insertions(+), 104 deletions(-)
