Quoting b5d8b03db136 ("x86/shadow: Drop dubious lastpage diagnostic"):
"This is a global variable (actually 3, one per GUEST_PAGING_LEVEL), operated
on using atomics only (with no regard to what else shares the same cacheline),
which emits a diagnostic (in debug builds only) without changing any program
behaviour.
It is presumably left-over debugging, as it interlinks the behaviour of all
vCPUs in chronological order. Based on the read-only p2m types, this
diagnostic can be tripped by entirely legitimate guest behaviour."
All the same applies here (it's only a single variable of course).
Signed-off-by: Jan Beulich <jbeul...@suse.com>
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3354,16 +3354,7 @@ static enum hvm_translation_result __hvm
memcpy(buf, p, count);
hvmemul_write_cache(v, gfn_to_gaddr(gfn) | pgoff, buf, count);
}
- else if ( p2m_is_discard_write(p2mt) )
- {
- static unsigned long lastpage;
-
- if ( xchg(&lastpage, gfn_x(gfn)) != gfn_x(gfn) )
- dprintk(XENLOG_G_DEBUG,
- "%pv attempted write to read-only gfn %#lx
(mfn=%#"PRI_mfn")\n",
- v, gfn_x(gfn), mfn_x(page_to_mfn(page)));
- }
- else
+ else if ( !p2m_is_discard_write(p2mt) )
{
if ( buf )
memcpy(p, buf, count);
