linux-kernel - [PATCH v8 00/15] KVM: xen: update shared_info and vcpu

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Message-Id: <20231121180223.12484-1-paul@xen.org>
Date:   Tue, 21 Nov 2023 18:02:08 +0000
From:   Paul Durrant <paul@....org>
To:     David Woodhouse <dwmw2@...radead.org>, Paul Durrant <paul@....org>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v8 00/15] KVM: xen: update shared_info and vcpu_info handling

From: Paul Durrant <pdurrant@...zon.com>

Currently the shared_info page is treated as guest memory and the VMM
informs KVM of its location using a GFN. However it is not guest memory as
such; it's an overlay page. So the pfncache is pointlessly invalidated and
re-activated to create a new mapping of the *same page* of memory every
time the guest requests that shared_info be mapped into its address space.
Avoid doing that by modifying the pfncache code to allow activation using
a fixed userspace HVA as well as a GPA.

Version 8 of the series has been substantially re-worked and includes
several clean-up patches, particlarly the non-trivial clean-up patches:
"pfncache: remove KVM_GUEST_USES_PFN usage" and "xen: split up
kvm_xen_set_evtchn_fast()". Each patch carries its own version history.

Paul Durrant (15):
  KVM: pfncache: Add a map helper function
  KVM: pfncache: remove unnecessary exports
  KVM: xen: mark guest pages dirty with the pfncache lock held
  KVM: pfncache: add a mark-dirty helper
  KVM: pfncache: remove KVM_GUEST_USES_PFN usage
  KVM: pfncache: stop open-coding offset_in_page()
  KVM: pfncache: include page offset in uhva and use it consistently
  KVM: pfncache: allow a cache to be activated with a fixed (userspace)
    HVA
  KVM: xen: allow shared_info to be mapped by fixed HVA
  KVM: xen: allow vcpu_info to be mapped by fixed HVA
  KVM: selftests / xen: map shared_info using HVA rather than GFN
  KVM: selftests / xen: re-map vcpu_info using HVA rather than GPA
  KVM: xen: advertize the KVM_XEN_HVM_CONFIG_SHARED_INFO_HVA capability
  KVM: xen: split up kvm_xen_set_evtchn_fast()
  KVM: xen: allow vcpu_info content to be 'safely' copied

 Documentation/virt/kvm/api.rst                |  53 +++-
 arch/x86/kvm/x86.c                            |   7 +-
 arch/x86/kvm/xen.c                            | 260 +++++++++++-------
 include/linux/kvm_host.h                      |  38 ++-
 include/linux/kvm_types.h                     |   8 -
 include/uapi/linux/kvm.h                      |   9 +-
 .../selftests/kvm/x86_64/xen_shinfo_test.c    |  59 +++-
 virt/kvm/pfncache.c                           | 175 ++++++------
 8 files changed, 374 insertions(+), 235 deletions(-)


base-commit: 45b890f7689eb0aba454fc5831d2d79763781677
---
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: David Woodhouse <dwmw2@...radead.org>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Sean Christopherson <seanjc@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: x86@...nel.org
-- 
2.39.2