Re: [PATCH 2/5] kvm/svm: enhance MOV CR intercept handler

[Avi Kivity]

On 12/07/2010 04:30 PM, Andre Przywara wrote:
Avi Kivity wrote:
On 12/07/2010 12:59 PM, Andre Przywara wrote:
Newer SVM implementations provide the GPR number in the VMCB, so
that the emulation path is no longer necesarry to handle CR
register access intercepts. Implement the handling in svm.c and
use it when the info is provided.
Signed-off-by: Andre Przywara<andre.przyw...@amd.com>
---
  arch/x86/include/asm/svm.h |    2 +
  arch/x86/kvm/svm.c         |   74 
+++++++++++++++++++++++++++++++++++++++-----
  2 files changed, 68 insertions(+), 8 deletions(-)

diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h
index 11dbca7..589fc25 100644
--- a/arch/x86/include/asm/svm.h
+++ b/arch/x86/include/asm/svm.h
...
@@ -2864,14 +2922,14 @@ static int pause_interception(struct 
vcpu_svm *svm)
  }

  static int (*svm_exit_handlers[])(struct vcpu_svm *svm) = {
-    [SVM_EXIT_READ_CR0]            = emulate_on_interception,
-    [SVM_EXIT_READ_CR3]            = emulate_on_interception,
-    [SVM_EXIT_READ_CR4]            = emulate_on_interception,
-    [SVM_EXIT_READ_CR8]            = emulate_on_interception,
+    [SVM_EXIT_READ_CR0]            = cr_interception,
+    [SVM_EXIT_READ_CR3]            = cr_interception,
+    [SVM_EXIT_READ_CR4]            = cr_interception,
+    [SVM_EXIT_READ_CR8]            = cr_interception,
      [SVM_EXIT_CR0_SEL_WRITE]        = emulate_on_interception,
      [SVM_EXIT_WRITE_CR0]            = cr0_write_interception,
-    [SVM_EXIT_WRITE_CR3]            = emulate_on_interception,
-    [SVM_EXIT_WRITE_CR4]            = emulate_on_interception,
+    [SVM_EXIT_WRITE_CR3]            = cr_interception,
+    [SVM_EXIT_WRITE_CR4]            = cr_interception,
      [SVM_EXIT_WRITE_CR8]            = cr8_write_interception,

We could move cr[08]_write_interception into cr_interception, but 
that takes a bit more thought.  Best done later.
Yes, I thought about that, too. But since we still have to deal with 
the emulation code path, it would not make the code easier. But if we 
overwrite the svm_exit_handlers[] on detecting the SVM feature, this 
could make more sense. I will check this out.


In fact the correct thing is to make sure kvm_set_cr0() and 
kvm_set_cr8() do the right thing, so that the emulation path invoked 
directly (not through a cr intercept) works.

--
error compiling committee.c: too many arguments to function

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