linux-kernel - Re: [PATCH 00/16] KVM: x86/mmu: Page fault and MMIO cleanups

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Message-ID: <CABgObfaS7RhUPe_FYS9SCuDzOfFw4X9P8XOhJSspVdzsYeoX2A@mail.gmail.com>
Date: Wed, 17 Apr 2024 14:48:08 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Yan Zhao <yan.y.zhao@...el.com>, Isaku Yamahata <isaku.yamahata@...el.com>, 
	Michael Roth <michael.roth@....com>, Yu Zhang <yu.c.zhang@...ux.intel.com>, 
	Chao Peng <chao.p.peng@...ux.intel.com>, Fuad Tabba <tabba@...gle.com>, 
	David Matlack <dmatlack@...gle.com>
Subject: Re: [PATCH 00/16] KVM: x86/mmu: Page fault and MMIO cleanups

On Wed, Feb 28, 2024 at 3:41 AM Sean Christopherson <seanjc@...gle.com> wrote:
>
> This is a combination of prep work for TDX and SNP, and a clean up of the
> page fault path to (hopefully) make it easier to follow the rules for
> private memory, noslot faults, writes to read-only slots, etc.
>
> Paolo, this is the series I mentioned in your TDX/SNP prep work series.
> Stating the obvious, these
>
>   KVM: x86/mmu: Pass full 64-bit error code when handling page faults
>   KVM: x86: Move synthetic PFERR_* sanity checks to SVM's #NPF handler
>
> are the drop-in replacements.

Applied to kvm-coco-queue, thanks, and these to kvm/queue as well:

 KVM: x86/mmu: Exit to userspace with -EFAULT if private fault hits emulation
 KVM: x86: Remove separate "bit" defines for page fault error code masks
 KVM: x86: Define more SEV+ page fault error bits/flags for #NPF
 KVM: x86: Move synthetic PFERR_* sanity checks to SVM's #NPF handler
 KVM: x86/mmu: Pass full 64-bit error code when handling page faults
 KVM: x86/mmu: WARN if upper 32 bits of legacy #PF error code are non-zero

I have made a little hack for kvm-coco-queue, preserving for now the
usage of PFERR_GUEST_ENC_MASK in case people were relying on the
branch, to limit the rebase pain.

The remaining parts are split into a "[TO SQUASH] KVM: x86/mmu: Use
synthetic page fault error code to indicate private faults" commit at
the end of the branch.

Paolo

> Isaku Yamahata (1):
>   KVM: x86/mmu: Pass full 64-bit error code when handling page faults
>
> Sean Christopherson (15):
>   KVM: x86/mmu: Exit to userspace with -EFAULT if private fault hits
>     emulation
>   KVM: x86: Remove separate "bit" defines for page fault error code
>     masks
>   KVM: x86: Define more SEV+ page fault error bits/flags for #NPF
>   KVM: x86/mmu: Use synthetic page fault error code to indicate private
>     faults
>   KVM: x86/mmu: WARN if upper 32 bits of legacy #PF error code are
>     non-zero
>   KVM: x86: Move synthetic PFERR_* sanity checks to SVM's #NPF handler
>   KVM: x86/mmu: WARN and skip MMIO cache on private, reserved page
>     faults
>   KVM: x86/mmu: Move private vs. shared check above slot validity checks
>   KVM: x86/mmu: Don't force emulation of L2 accesses to non-APIC
>     internal slots
>   KVM: x86/mmu: Explicitly disallow private accesses to emulated MMIO
>   KVM: x86/mmu: Move slot checks from __kvm_faultin_pfn() to
>     kvm_faultin_pfn()
>   KVM: x86/mmu: Handle no-slot faults at the beginning of
>     kvm_faultin_pfn()
>   KVM: x86/mmu: Set kvm_page_fault.hva to KVM_HVA_ERR_BAD for "no slot"
>     faults
>   KVM: x86/mmu: Initialize kvm_page_fault's pfn and hva to error values
>   KVM: x86/mmu: Sanity check that __kvm_faultin_pfn() doesn't create
>     noslot pfns
>
>  arch/x86/include/asm/kvm_host.h |  45 ++++-----
>  arch/x86/kvm/mmu.h              |   4 +-
>  arch/x86/kvm/mmu/mmu.c          | 159 +++++++++++++++++++-------------
>  arch/x86/kvm/mmu/mmu_internal.h |  24 ++++-
>  arch/x86/kvm/mmu/mmutrace.h     |   2 +-
>  arch/x86/kvm/svm/svm.c          |   9 ++
>  6 files changed, 151 insertions(+), 92 deletions(-)
>
>
> base-commit: ec1e3d33557babed2c2c2c7da6e84293c2f56f58
> --
> 2.44.0.278.ge034bb2e1d-goog
>