On 01/20/2016 05:52 PM, Roman Kagan wrote:
On Wed, Jan 20, 2016 at 05:44:49PM +0300, Denis V. Lunev wrote:
On 01/20/2016 05:05 PM, Paolo Bonzini wrote:
On 19/01/2016 08:48, Denis V. Lunev wrote:
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 6877b4d7e..93c9e25 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -145,6 +145,7 @@ static inline bool is_error_page(struct page *page)
#define KVM_REQ_HV_RESET 29
#define KVM_REQ_HV_EXIT 30
#define KVM_REQ_HV_STIMER 31
+#define KVM_REQ_HV_TSC_PAGE 32
#define KVM_REQ_MAX 64
ping
Applied with this change:
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index d7716c6e2752..047c275717d3 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -842,7 +842,7 @@ int kvm_hv_setup_tsc_page(struct kvm_vcpu *vcpu)
tsc_khz, tsc, tsc_scale, tsc_offset);
tsc_ref.tsc_sequence++;
- if (tsc_ref.tsc_sequence == 0)
+ if (tsc_ref.tsc_sequence == 0xFFFFFFFF tsc_ref.tsc_sequence == 0)
tsc_ref.tsc_sequence = 1;
tsc_ref.tsc_scale = tsc_scale;
and renumbering KVM_REQ_HV_TSC_PAGE from 32 to 31.
Paolo
the latter does not seem to be correct to me.
MS spec has bug, see this thread:
https://lkml.org/lkml/2015/11/2/655
and the change was Acked-by: K.Y.
What happens in the patched code is this: when the sequence counter
wraps around and hits an invalid value, skip to the next valid one.
I think Paolo wanted to be compatible not only with the de facto
implementation in Windows Hyper-V guests, but also with the Linux driver
which followed the buggy spec and thought 0xFFFFFFFF to be invalid.
So the change is fine (as long as there's || rather than a space there
;)
this seems reasonable, you are right :)
Thank you for the explanation.
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