linux-kernel - Re: [PATCH 00/10] KVM/X86: Handle guest memory that does not have a struct page

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Message-ID: <1519917874.15908.41.camel@amazon.de>
Date:   Thu, 1 Mar 2018 15:24:34 +0000
From:   "Raslan, KarimAllah" <karahmed@...zon.de>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>
CC:     "hpa@...or.com" <hpa@...or.com>,
        "jmattson@...gle.com" <jmattson@...gle.com>,
        "rkrcmar@...hat.com" <rkrcmar@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "pbonzini@...hat.com" <pbonzini@...hat.com>
Subject: Re: [PATCH 00/10] KVM/X86: Handle guest memory that does not have a
 struct page

Jim/Paolo/Radim,

Any complains about the current API? (introduced in 4/10)

I have more patches on top and I would like to ensure that this is 
agreed upon at least before sending more revisions/patches.

Also 1, 2, and 3 should be a bit straight forward and does not use 
this API.

Thanks.

On Wed, 2018-02-21 at 18:47 +0100, KarimAllah Ahmed wrote:
> For the most part, KVM can handle guest memory that does not have a struct
> page (i.e. not directly managed by the kernel). However, There are a few places
> in the code, specially in the nested code, that does not support that.
> 
> Patch 1, 2, and 3 avoid the mapping and unmapping all together and just
> directly use kvm_guest_read and kvm_guest_write.
> 
> Patch 4 introduces a new guest mapping interface that encapsulate all the
> bioler plate code that is needed to map and unmap guest memory. It also
> supports guest memory without "struct page".
> 
> Patch 5, 6, 7, 8, 9, and 10 switch most of the offending code in VMX and hyperv
> to use the new guest mapping API.
> 
> This patch series is the first set of fixes. Handling SVM and APIC-access page
> will be handled in a different patch series.
> 
> KarimAllah Ahmed (10):
>   X86/nVMX: handle_vmon: Read 4 bytes from guest memory instead of
>     map->read->unmap sequence
>   X86/nVMX: handle_vmptrld: Copy the VMCS12 directly from guest memory
>     instead of map->copy->unmap sequence.
>   X86/nVMX: Update the PML table without mapping and unmapping the page
>   KVM: Introduce a new guest mapping API
>   KVM/nVMX: Use kvm_vcpu_map when mapping the L1 MSR bitmap
>   KVM/nVMX: Use kvm_vcpu_map when mapping the virtual APIC page
>   KVM/nVMX: Use kvm_vcpu_map when mapping the posted interrupt
>     descriptor table
>   KVM/X86: Use kvm_vcpu_map in emulator_cmpxchg_emulated
>   KVM/X86: hyperv: Use kvm_vcpu_map in synic_clear_sint_msg_pending
>   KVM/X86: hyperv: Use kvm_vcpu_map in synic_deliver_msg
> 
>  arch/x86/kvm/hyperv.c    |  28 ++++-----
>  arch/x86/kvm/vmx.c       | 144 +++++++++++++++--------------------------------
>  arch/x86/kvm/x86.c       |  13 ++---
>  include/linux/kvm_host.h |  15 +++++
>  virt/kvm/kvm_main.c      |  50 ++++++++++++++++
>  5 files changed, 129 insertions(+), 121 deletions(-)
> 
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