Messages in this thread | | | Date | Wed, 29 Jun 2011 11:37:43 +0300 | From | Avi Kivity <> | Subject | Re: [PATCH v2 05/22] KVM: x86: abstract the operation for read/write emulation |
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On 06/22/2011 05:30 PM, Xiao Guangrong wrote: > The operations of read emulation and write emulation are very similar, so we > can abstract the operation of them, in larter patch, it is used to cleanup the > same code > > Signed-off-by: Xiao Guangrong<xiaoguangrong@cn.fujitsu.com> > --- > arch/x86/kvm/x86.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 files changed, 72 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index c29ef96..887714f 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -4056,6 +4056,78 @@ int emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa, > return 1; > } > > +struct read_write_emulator_ops { > + int (*read_write_prepare)(struct kvm_vcpu *vcpu, void *val, > + int bytes); > + int (*read_write_emulate)(struct kvm_vcpu *vcpu, gpa_t gpa, > + void *val, int bytes); > + int (*read_write_mmio)(struct kvm_vcpu *vcpu, gpa_t gpa, > + int bytes, void *val); > + int (*read_write_exit_mmio)(struct kvm_vcpu *vcpu, gpa_t gpa, > + void *val, int bytes); > + bool write; > +};
Interesting!
This structure combines two unrelated operations, though. One is the internals of the iteration on a virtual address that is split to various physical addresses. The other is the interaction with userspace on mmio exits. They should be split, but I think it's fine to do it in a later patch. This series is long enough already.
I was also annoyed by the duplication. They way I thought of fixing it is having gva_to_gpa() return two gpas, and having the access function accept gpa vectors. The reason was so that we can implemented locked cross-page operations (which we now emulate as unlocked writes).
But I think we can do without it, and instead emulated locked cross-page ops by stalling all other vcpus while we write, or by unmapping the pages involved. It isn't pretty but it doesn't need to be fast since it's a very rare operation. So I think we can go with your approach.
-- error compiling committee.c: too many arguments to function
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