From: Paolo Bonzini <pbonzini@redhat.com>
To: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org, kvm@vger.kernel.org,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Ralf Baechle" <ralf@linux-mips.org>,
"Jonathan Corbet" <corbet@lwn.net>,
linux-doc@vger.kernel.org
Subject: Re: [PATCH 11/32] KVM: MIPS: Add VZ capability
Date: Thu, 2 Mar 2017 13:20:05 +0100 [thread overview]
Message-ID: <1a071956-a897-a2f9-4523-e6da074568b6@redhat.com> (raw)
In-Reply-To: <20170302113923.GC2878@jhogan-linux.le.imgtec.org>
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On 02/03/2017 12:39, James Hogan wrote:
> It can't right now, though with relocation of the kernel now implemented
> in MIPS Linux for KASLR, and hopes for a more generic EVA implementation
> (which can require the kernel to be linked in a completely different
> segment) it isn't completely infeasible.
What about the other way round, sticking a minimal T&E stub in kernel
space and running the kernel in userspace? Would it be feasible or
would it be as complex as KVM itself?
> 1) QEMU, which I've implemented using the kvm_type machine callback.
> This allows the KVM type to be specified with e.g.
> "-machine malta,accel=kvm,kvm-type=TE"
> Otherwise it defaults to using KVM_VM_MIPS_DEFAULT.
>
> When you try and load a kernel (which happens after kvm_init() has
> already passed the kvm type into KVM_CREATE_VM) it will check that it
> supports the current kernel type.
>
> 2) My kvm test application, which uses KVM_VM_MIPS_DEFAULT by default
> and hackily maps itself into the guest physical address space to run C
> code test cases.
So this one would work for both TE and VZ because the guest is not a
Linux kernel.
I don't know... Instinctively I would think that it's easy to get
KVM_VM_MIPS_DEFAULT wrong and place the VZ-and-fall-back-to-TE policy in
userspace, but I can be convinced otherwise if the failure mode is good
enough. For example, what happens if you use KVM_SET_USER_MEMORY_REGION
for a kernel address in TE mode?
Paolo
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next prev parent reply other threads:[~2017-03-02 12:20 UTC|newest]
Thread overview: 72+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-02 9:36 [PATCH 0/32] KVM: MIPS: Add VZ support James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 1/32] MIPS: Add defs & probing of UFR James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 2/32] MIPS: Separate MAAR V bit into VL and VH for XPA James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 3/32] MIPS: Probe guest CP0_UserLocal James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 4/32] MIPS: Probe guest MVH James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 5/32] MIPS: Add some missing guest CP0 accessors & defs James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 6/32] MIPS: asm/tlb.h: Add UNIQUE_GUEST_ENTRYHI() macro James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 7/32] KVM: MIPS/Emulate: De-duplicate MMIO emulation James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 8/32] KVM: MIPS/Emulate: Implement 64-bit " James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 9/32] KVM: MIPS: Update kvm_lose_fpu() for VZ James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 10/32] KVM: MIPS: Extend counters & events for VZ GExcCodes James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 11/32] KVM: MIPS: Add VZ capability James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 10:59 ` Paolo Bonzini
2017-03-02 11:39 ` James Hogan
2017-03-02 12:20 ` Paolo Bonzini [this message]
2017-03-02 22:34 ` James Hogan
2017-03-03 12:37 ` James Hogan
2017-03-03 12:41 ` Paolo Bonzini
2017-03-02 9:36 ` [PATCH 12/32] KVM: MIPS: Add 64BIT capability James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 13/32] KVM: MIPS: Init timer frequency from callback James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 14/32] KVM: MIPS: Add callback to check extension James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 15/32] KVM: MIPS: Add hardware_{enable,disable} callback James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 16/32] KVM: MIPS: Add guest exit exception callback James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 17/32] KVM: MIPS: Abstract guest CP0 register access for VZ James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 18/32] KVM: MIPS/Entry: Update entry code to support VZ James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 19/32] KVM: MIPS/TLB: Add VZ TLB management James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 20/32] KVM: MIPS/Emulate: Update CP0_Compare emulation for VZ James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 21/32] KVM: MIPS/Emulate: Drop CACHE " James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 22/32] KVM: MIPS: Update exit handler " James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 23/32] KVM: MIPS: Implement VZ support James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 24/32] KVM: MIPS: Add VZ support to build system James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 25/32] KVM: MIPS/VZ: Support guest CP0_BadInstr[P] James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 26/32] KVM: MIPS/VZ: Support guest CP0_[X]ContextConfig James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 27/32] KVM: MIPS/VZ: Support guest segmentation control James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 28/32] KVM: MIPS/VZ: Support guest hardware page table walker James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 29/32] KVM: MIPS/VZ: Support guest load-linked bit James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 30/32] KVM: MIPS/VZ: Emulate MAARs when necessary James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 31/32] KVM: MIPS/VZ: Support hardware guest timer James Hogan
2017-03-02 9:36 ` James Hogan
2017-03-02 9:36 ` [PATCH 32/32] KVM: MIPS/VZ: Trace guest mode changes James Hogan
2017-03-02 9:36 ` James Hogan
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