Hi Paolo,
Something bad happened to this patch. This is the version I provided
Tested-by for:
On Thu, 2015-07-16 at 03:25 +0800, Xiao Guangrong wrote:
> From: Xiao Guangrong <guangrong.xiao@xxxxxxxxx>
>
> kvm_mtrr_get_guest_memory_type never returns -1 which is implied
> in the current code since if @type = -1 (means no MTRR contains the
> range), iter.partial_map must be true
>
> Simplify the code to indicate this fact
>
> Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxx>
> ---
> arch/x86/kvm/mtrr.c | 19 ++++++++++---------
> 1 file changed, 10 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
> index e275013..9e8bf13 100644
> --- a/arch/x86/kvm/mtrr.c
> +++ b/arch/x86/kvm/mtrr.c
> @@ -672,15 +672,16 @@ u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
> if (iter.mtrr_disabled)
> return mtrr_disabled_type();
>
> - /* It is not covered by MTRRs. */
> - if (iter.partial_map) {
> - /*
> - * We just check one page, partially covered by MTRRs is
> - * impossible.
> - */
> - WARN_ON(type != -1);
> - type = mtrr_default_type(mtrr_state);
> - }
> + /* not contained in any MTRRs. */
> + if (type == -1)
> + return mtrr_default_type(mtrr_state);
> +
> + /*
> + * We just check one page, partially covered by MTRRs is
> + * impossible.
> + */
> + WARN_ON(iter.partial_map);
> +
> return type;
> }
> EXPORT_SYMBOL_GPL(kvm_mtrr_get_guest_memory_type);
This is the version that was committed for v4.2-rc4:
commit 3e5d2fdceda172554e681b68c853bf5d08205bbf
Author: Xiao Guangrong <guangrong.xiao@xxxxxxxxx>
Date: Thu Jul 16 03:25:55 2015 +0800
KVM: MTRR: simplify kvm_mtrr_get_guest_memory_type
kvm_mtrr_get_guest_memory_type never returns -1 which is implied
in the current code since if @type = -1 (means no MTRR contains the
range), iter.partial_map must be true
Simplify the code to indicate this fact
Signed-off-by: Xiao Guangrong <guangrong.xiao@xxxxxxxxx>
Tested-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
index e275013..dc0a84a 100644
--- a/arch/x86/kvm/mtrr.c
+++ b/arch/x86/kvm/mtrr.c
@@ -672,15 +672,16 @@ u8 kvm_mtrr_get_guest_memory_type(struct kvm_vcpu *vcpu, gfn_t gfn)
if (iter.mtrr_disabled)
return mtrr_disabled_type();
- /* It is not covered by MTRRs. */
- if (iter.partial_map) {
- /*
- * We just check one page, partially covered by MTRRs is
- * impossible.
- */
- WARN_ON(type != -1);
- type = mtrr_default_type(mtrr_state);
- }
+ /*
+ * We just check one page, partially covered by MTRRs is
+ * impossible.
+ */
+ WARN_ON(iter.partial_map);
+
+ /* not contained in any MTRRs. */
+ if (type == -1)
+ return mtrr_default_type(mtrr_state);
+
return type;
}
EXPORT_SYMBOL_GPL(kvm_mtrr_get_guest_memory_type);
The WARN_ON() now comes before the type == -1 test and I hit that at
*very* high frequency when trying to test device assignment. Restoring
the ordering to what Xiao originally proposed resolves the problem.
Thanks,
Alex
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