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Re: [Xen-devel] [PATCH] x86/vtsc: update vcpu_time after hvm_set_guest_time


--On 4 June 2013 11:10:50 +0200 Roger Pau Monne <roger.pau@xxxxxxxxxx> wrote:

When using a vtsc, hvm_set_guest_time changes hvm_vcpu.stime_offset,
which is used in the vcpu time structure to calculate the
tsc_timestamp, so after updating stime_offset we need to propagate the
change to vcpu_time in order for the guest to get the right time if
using the PV clock.

This was not done correctly, since in context_switch
update_vcpu_system_time was called before vmx_do_resume, which caused
the vcpu_info time structure to be updated with the wrong values. This
patch fixes this by calling update_vcpu_system_time after the call to
hvm_set_guest_time has happened.
I think this is the 'proper' fix to the bug Diana reported about
stuck clock - can you confirm? If so, we're happy to test this on
4.3 and/or do try our hand at a backport to 4.2.

Alex Bligh

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