From: Avi Kivity <avi@redhat.com>
To: "Nadav Har'El" <nyh@math.technion.ac.il>
Cc: kvm@vger.kernel.org, gleb@redhat.com
Subject: Re: [PATCH 10/27] nVMX: Implement VMCLEAR
Date: Sun, 17 Oct 2010 16:12:35 +0200 [thread overview]
Message-ID: <4CBB0453.6050002@redhat.com> (raw)
In-Reply-To: <20101017133700.GE14069@fermat.math.technion.ac.il>
On 10/17/2010 03:37 PM, Nadav Har'El wrote:
> On Sun, Oct 17, 2010, Avi Kivity wrote about "Re: [PATCH 10/27] nVMX: Implement VMCLEAR":
> > Is something preventing you from changing all kmap()s to kmap_atomic()s
> > (like guest memory access in the mapped section)?
>
> Yes. We've discussed this before, and I know you suggested other alternatives,
> but the way we currently work with vmcs12 (the page of memory that L1 maintains
> as its VMCS for its L2 guest) is this: When L1 uses VMPTRLD to set the current
> VMCS, we pin this page and kmap it, and keep a pointer to it immediately
> accessible throughout the code. The page is only unmapped and released when
> L1 is done with this VMCS (i.e., calls VMPTRLD again, or VMCLEAR, or of course
> terminates).
>
> The nice thing about this approach, over the alternatives, is that it is
> more efficient than special guest_read/write calls (accesses to vmcs12 are
> ordinary memory accesses) and the code is simpler than it was previously
> with map/unmap pairs around every access.
>
> Obviously, I can't use kmap_atomic() when the mapping is to live a long time,
> also outside atomic constant. This could lead to bugs if two parts of the
> Kernel use the same kmap_atomic() "slot" :(
>
Ok. Let's keep it for now. But look at
http://thread.gmane.org/gmane.comp.emulators.kvm.devel/60920 for a much
nicer way to to this (y, can you add kvm_read_guest_cached()?)
Sorry about repeating old arguments, I kunmap_atomic() everything
immediately after I review it.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2010-10-17 14:12 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-10-17 10:03 [PATCH 0/27] nVMX: Nested VMX, v6 Nadav Har'El
2010-10-17 10:04 ` [PATCH 01/27] nVMX: Add "nested" module option to vmx.c Nadav Har'El
2010-10-17 10:04 ` [PATCH 02/27] nVMX: Add VMX and SVM to list of supported cpuid features Nadav Har'El
2010-10-17 10:05 ` [PATCH 03/27] nVMX: Implement VMXON and VMXOFF Nadav Har'El
2010-10-17 12:24 ` Avi Kivity
2010-10-17 12:47 ` Nadav Har'El
2010-10-17 13:07 ` Avi Kivity
2010-10-17 10:05 ` [PATCH 04/27] nVMX: Allow setting the VMXE bit in CR4 Nadav Har'El
2010-10-17 12:31 ` Avi Kivity
2010-10-17 10:06 ` [PATCH 05/27] nVMX: Introduce vmcs12: a VMCS structure for L1 Nadav Har'El
2010-10-17 12:34 ` Avi Kivity
2010-10-17 13:18 ` Nadav Har'El
2010-10-17 13:29 ` Avi Kivity
2010-10-17 10:06 ` [PATCH 06/27] nVMX: Implement reading and writing of VMX MSRs Nadav Har'El
2010-10-17 12:52 ` Avi Kivity
2010-10-17 10:07 ` [PATCH 07/27] nVMX: Decoding memory operands of VMX instructions Nadav Har'El
2010-10-17 10:07 ` [PATCH 08/27] nVMX: Hold a vmcs02 for each vmcs12 Nadav Har'El
2010-10-17 13:00 ` Avi Kivity
2010-10-17 10:08 ` [PATCH 09/27] nVMX: Success/failure of VMX instructions Nadav Har'El
2010-10-17 10:08 ` [PATCH 10/27] nVMX: Implement VMCLEAR Nadav Har'El
2010-10-17 13:05 ` Avi Kivity
2010-10-17 13:25 ` Nadav Har'El
2010-10-17 13:27 ` Avi Kivity
2010-10-17 13:37 ` Nadav Har'El
2010-10-17 14:12 ` Avi Kivity [this message]
2010-10-17 14:14 ` Gleb Natapov
2010-10-17 10:09 ` [PATCH 11/27] nVMX: Implement VMPTRLD Nadav Har'El
2010-10-17 10:09 ` [PATCH 12/27] nVMX: Implement VMPTRST Nadav Har'El
2010-10-17 10:10 ` [PATCH 13/27] nVMX: Add VMCS fields to the vmcs12 Nadav Har'El
2010-10-17 13:15 ` Avi Kivity
2010-10-17 10:10 ` [PATCH 14/27] nVMX: Implement VMREAD and VMWRITE Nadav Har'El
2010-10-17 13:25 ` Avi Kivity
2010-10-17 10:11 ` [PATCH 15/27] nVMX: Prepare vmcs02 from vmcs01 and vmcs12 Nadav Har'El
2010-10-17 14:08 ` Avi Kivity
2011-02-08 12:13 ` Nadav Har'El
2011-02-08 12:27 ` Avi Kivity
2011-02-08 12:36 ` Nadav Har'El
2011-02-08 12:39 ` Avi Kivity
2011-02-08 12:27 ` Avi Kivity
2010-10-17 10:11 ` [PATCH 16/27] nVMX: Move register-syncing to a function Nadav Har'El
2010-10-17 10:12 ` [PATCH 17/27] nVMX: Implement VMLAUNCH and VMRESUME Nadav Har'El
2010-10-17 15:06 ` Avi Kivity
2010-10-17 10:12 ` [PATCH 18/27] nVMX: No need for handle_vmx_insn function any more Nadav Har'El
2010-10-17 10:13 ` [PATCH 19/27] nVMX: Exiting from L2 to L1 Nadav Har'El
2010-10-17 15:58 ` Avi Kivity
2010-10-17 10:13 ` [PATCH 20/27] nVMX: Deciding if L0 or L1 should handle an L2 exit Nadav Har'El
2010-10-20 12:13 ` Avi Kivity
2010-10-20 14:57 ` Avi Kivity
2010-10-17 10:14 ` [PATCH 21/27] nVMX: Correct handling of interrupt injection Nadav Har'El
2010-10-17 10:14 ` [PATCH 22/27] nVMX: Correct handling of exception injection Nadav Har'El
2010-10-17 10:15 ` [PATCH 23/27] nVMX: Correct handling of idt vectoring info Nadav Har'El
2010-10-17 10:15 ` [PATCH 24/27] nVMX: Handling of CR0.TS and #NM for Lazy FPU loading Nadav Har'El
2010-10-17 10:16 ` [PATCH 25/27] nVMX: Additional TSC-offset handling Nadav Har'El
2010-10-19 19:13 ` Zachary Amsden
2010-10-17 10:16 ` [PATCH 26/27] nVMX: Miscellenous small corrections Nadav Har'El
2010-10-17 10:17 ` [PATCH 27/27] nVMX: Documentation Nadav Har'El
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