The current HVM default for writes to unknown MSRs is to inject #GP if the MSR
is unreadable, and discard writes otherwise. While this behaviour isn't great,
the PV default is even worse, because it swallows writes even to non-readable
MSRs. i.e. A PV guest doesn't even get a #GP fault for a write to a totally
bogus index.
Update PV to make it consistent with HVM, which will simplify the task of
making other improvements to the default MSR behaviour.
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: Jan Beulich <jbeul...@suse.com>
CC: Wei Liu <w...@xen.org>
CC: Roger Pau Monné <roger....@citrix.com>
---
xen/arch/x86/pv/emul-priv-op.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/xen/arch/x86/pv/emul-priv-op.c b/xen/arch/x86/pv/emul-priv-op.c
index f14552cb4b..efeb2a727e 100644
--- a/xen/arch/x86/pv/emul-priv-op.c
+++ b/xen/arch/x86/pv/emul-priv-op.c
@@ -1113,7 +1113,10 @@ static int write_msr(unsigned int reg, uint64_t val,
}
/* fall through */
default:
- if ( (rdmsr_safe(reg, temp) != 0) || (val != temp) )
+ if ( rdmsr_safe(reg, temp) )
+ break;
+
+ if ( val != temp )
invalid:
gdprintk(XENLOG_WARNING,
"Domain attempted WRMSR %08x from 0x%016"PRIx64" to
0x%016"PRIx64"\n",
--
2.11.0
