File 5db07974-x86-update-time-info-on-TSC-adjustment... of Package xen.20938

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File 5db07974-x86-update-time-info-on-TSC-adjustments.patch of Package xen.20938

# Commit 7eee9c16d6405a1a1f2e8c6472923db842c90cfb
# Date 2019-10-23 17:01:56 +0100
# Author Roger Pau Monné <roger.pau@citrix.com>
# Committer Andrew Cooper <andrew.cooper3@citrix.com>
x86/tsc: update vcpu time info on guest TSC adjustments

If a HVM/PVH guest writes to MSR_IA32_TSC{_ADJUST} and thus changes
the value of the time stamp counter the vcpu time info must also be
updated, or the time calculated by the guest using the Xen PV clock
interface will be skewed.

Update the vcpu time info when the guest writes to either MSR_IA32_TSC
or MSR_IA32_TSC_ADJUST. This fixes lockups seen when running the
pv-shim on AMD hardware, since the shim will aggressively try to keep
TSCs in sync by periodically writing to MSR_IA32_TSC if the TSC is not
reliable.

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Wei Liu <wl@xen.org>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -426,6 +426,8 @@ static void hvm_set_guest_tsc_msr(struct
     hvm_set_guest_tsc(v, guest_tsc);
     v->arch.hvm_vcpu.msr_tsc_adjust += v->arch.hvm_vcpu.cache_tsc_offset
                           - tsc_offset;
+    if ( v == current )
+        update_vcpu_system_time(v);
 }
 
 static void hvm_set_guest_tsc_adjust(struct vcpu *v, u64 tsc_adjust)
@@ -434,6 +436,8 @@ static void hvm_set_guest_tsc_adjust(str
                             - v->arch.hvm_vcpu.msr_tsc_adjust;
     hvm_funcs.set_tsc_offset(v, v->arch.hvm_vcpu.cache_tsc_offset, 0);
     v->arch.hvm_vcpu.msr_tsc_adjust = tsc_adjust;
+    if ( v == current )
+        update_vcpu_system_time(v);
 }
 
 u64 hvm_get_guest_tsc_fixed(struct vcpu *v, uint64_t at_tsc)

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File 5db07974-x86-update-time-info-on-TSC-adjustments.patch of Package xen.20938

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