linux-kernel - [PATCH v3 0/8] Introduce KVM_{GET|SET}

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Message-Id: <20210607090203.133058-1-mlevitsk@redhat.com>
Date:   Mon,  7 Jun 2021 12:01:55 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        linux-kernel@...r.kernel.org (open list),
        linux-doc@...r.kernel.org (open list:DOCUMENTATION),
        Wanpeng Li <wanpengli@...cent.com>,
        Ingo Molnar <mingo@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Sean Christopherson <seanjc@...gle.com>,
        Borislav Petkov <bp@...en8.de>, Joerg Roedel <joro@...tes.org>,
        x86@...nel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)),
        Jim Mattson <jmattson@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        "H. Peter Anvin" <hpa@...or.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v3 0/8] Introduce KVM_{GET|SET}_SREGS2 and fix PDPTR migration

This patch set aims to fix few flaws that were discovered
in KVM_{GET|SET}_SREGS on x86:

* There is no support for reading/writing PDPTRs although
  these are considered to be part of the guest state.

* There is useless interrupt bitmap which isn't needed

* No support for future extensions (via flags and such)

Also if the user doesn't use the new SREG2 api, the PDPTR
load after migration is now done on KVM_REQ_GET_NESTED_STATE_PAGES
to at least read them correctly in cases when guest memory
map is not up to date when nested state is loaded.

This patch series was tested by doing nested migration test
of 32 bit PAE L1 + 32 bit PAE L2 on AMD and Intel and by
nested migration test of 64 bit L1 + 32 bit PAE L2 on AMD.
The later test currently fails on Intel (regardless of my patches).

Changes from V2:
  - I took in the patch series from Sean Christopherson that
    removes the pdptrs_changed function and rebased my code
    on top of it.
  - I updated the SET_SREGS2 ioctl to load PDPTRS from memory
    when user haven't given PDPTRS.
  - Minor refactoring all over the place.

Changes from V1:
  - move only PDPTRS load to KVM_REQ_GET_NESTED_STATE_PAGES on VMX
  - rebase on top of kvm/queue
  - improve the KVM_GET_SREGS2 to have flag for PDPTRS
    and remove padding

Patches to qemu to enable this feature were sent as well.

Maxim Levitsky (5):
  KVM: nSVM: refactor the CR3 reload on migration
  KVM: nVMX: delay loading of PDPTRs to KVM_REQ_GET_NESTED_STATE_PAGES
  KVM: x86: introduce kvm_register_clear_available
  KVM: x86: Introduce KVM_GET_SREGS2 / KVM_SET_SREGS2
  KVM: x86: avoid loading PDPTRs after migration when possible

Sean Christopherson (3):
  KVM: nVMX: Drop obsolete (and pointless) pdptrs_changed() check
  KVM: nSVM: Drop pointless pdptrs_changed() check on nested transition
  KVM: x86: Always load PDPTRs on CR3 load for SVM w/o NPT and a PAE
    guest

 Documentation/virt/kvm/api.rst  |  48 +++++++++
 arch/x86/include/asm/kvm_host.h |   7 +-
 arch/x86/include/uapi/asm/kvm.h |  13 +++
 arch/x86/kvm/kvm_cache_regs.h   |  12 +++
 arch/x86/kvm/svm/nested.c       |  39 +++++--
 arch/x86/kvm/svm/svm.c          |   6 +-
 arch/x86/kvm/vmx/nested.c       |  32 ++++--
 arch/x86/kvm/x86.c              | 176 +++++++++++++++++++++-----------
 include/uapi/linux/kvm.h        |   4 +
 9 files changed, 253 insertions(+), 84 deletions(-)

-- 
2.26.3