From: Hollis Blanchard <hollis-yUx37fBWTUITNcAmw9vGhQ@public.gmane.org>
To: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org
Subject: kvm_regs vs kvm_sregs?
Date: Fri, 16 Mar 2007 10:00:54 -0500 [thread overview]
Message-ID: <1174057254.22955.13.camel@basalt> (raw)
What is the distinction between kvm_regs and kvm_sregs? As far as I can
see, kvm_regs is only used when emulating IO, emulating MMIO, and
emulating CPUID, where guest GPRs are directly modified. kvm_sregs is
only used for full CPU state save (for later restore).
When the kernel had to use copy_to_user() to transfer state to userland,
I can see that this split resulted in less memory copying. However, now
that userland can directly map register state without a copy, why not
combine the two structures?
I guess it takes longer to copy state out of the VMCS into kvm_sregs, so
why bother if userspace isn't going to use it?
-Hollis
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next reply other threads:[~2007-03-16 15:00 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-16 15:00 Hollis Blanchard [this message]
2007-03-18 5:13 ` kvm_regs vs kvm_sregs? Avi Kivity
[not found] ` <45FCCA6D.3070207-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2007-03-23 1:17 ` Hollis Blanchard
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