[Patch v2 0/4] Defer page pinning for SEV guests until guest pages touched

From: eric van tassell
Date: Wed Aug 19 2020 - 11:17:11 EST


Overview
========
Defer pinning of the guest's pages until nested page faults occur
to improve startup time and reduce memory pressure for SEV guests.

Cease paying the computational cost of pinning all pages when an
encrypted region is registered, before it is known if they will be accessed.

Cease creating the memory pressure due to pinning all pages when an
encrypted region is registered before, it is known if they will be accessed.

Timing Results
==========
All timings are done by hand with and Android stopwatch app

SEV guest size(GiB) | 4 | 8 | 16 | 32 | 60 |
without patch series(sec) | 2 | 3 | 4 | 8 | 14 |
with patch series (sec) | 1 | 1 | 1 | 1 | 1 |

Patch Series Changelog
==============
1 -> 2:
* mmio checks move from sev_pin_page() to caller and the
set_spte_notify* symbols are renamed to pin_page().

* sev_get_page() warns on failures which should not happen.

* kvm->srcu is used to avoid any possibility of a race in
sev_launch_update_data()
Applies To:
===========
This patch applies top of this commit from the <next> branch of
the kvm tree:
c34b26b98cac Tianjia Zhang : KVM: MIPS: clean up redundant 'kvm_run' parameters

eric van tassell (4):
KVM:MMU: Introduce the pin_page() callback
KVM:SVM: Implement pin_page support
KVM:SVM: Pin sev_launch_update_data() pages via sev_get_page()
KVM:SVM: Remove struct enc_region and associated pinned page tracking.

arch/x86/include/asm/kvm_host.h | 3 +
arch/x86/kvm/mmu/mmu.c | 30 +++-
arch/x86/kvm/mmu/paging_tmpl.h | 27 ++--
arch/x86/kvm/svm/sev.c | 238 +++++++++++++++++---------------
arch/x86/kvm/svm/svm.c | 2 +
arch/x86/kvm/svm/svm.h | 4 +-
6 files changed, 174 insertions(+), 130 deletions(-)

--
2.17.1