Intel VMX cannot intercept guest clwb and clflushopt. When clwb and
clflushopt are not exposed in guest cpuid, clwb and clflushopt
instructions in this test case can still succeed without #UD on the
host CPU which has clwb and clflushopt support, though failures with
UD are expected.
In order to avoid false alarms in such cases, introduce the following
two arguments "has_clwb" and "has_clflushopt" to allow users to
specify whether clwb and clflushopt are supported on the host CPU.
Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
---
x86/memory.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)
diff --git a/x86/memory.c b/x86/memory.c
index cd1eb46..03ff7d3 100644
--- a/x86/memory.c
+++ b/x86/memory.c
@@ -23,10 +23,29 @@ static void handle_ud(struct ex_regs *regs)
regs->rip += isize;
}
+/*
+ * Intel VMX cannot intercept guest clwb and clflushopt. When clwb and
+ * clflushopt are not exposed in guest cpuid, clwb and clflushopt
+ * instructions in this test case can still succeed without #UD on
+ * the host CPU which has clwb and clflushopt support. In order to avoid
+ * false alarms in such cases, introduce the following two arguments
+ * to allow users to specify whether clwb and clflushopt are supported on
+ * the host CPU:
+ * - has_clwb: indicates clwb is supported on the host CPU
+ * - has_clflushopt: indicates clflushopt is supported on the host CPU
+ */
int main(int ac, char **av)
{
struct cpuid cpuid7, cpuid1;
int xfail;
+ int host_has_clwb = 0, host_has_clflushopt = 0; /* 0: unknown */
+ int i;
+
+ for (i = 1; i < ac; i++)
+ if (!strcmp(av[i], "has_clwb"))
+ host_has_clwb = 1;
+ else if (!strcmp(av[i], "has_clflushopt"))
+ host_has_clflushopt = 1;
setup_idt();
handle_exception(UD_VECTOR, handle_ud);
@@ -63,13 +82,19 @@ int main(int ac, char **av)
ud = 0;
/* clflushopt (%rbx): */
asm volatile(".byte 0x66, 0x0f, 0xae, 0x3b" : : "b" (&target));
- report_xfail("clflushopt", xfail, ud == 0);
+ if (host_has_clflushopt)
+ report("clflushopt", ud == 0);
+ else
+ report_xfail("clflushopt", xfail, ud == 0);
xfail = !(cpuid7.b & (1U << 24)); /* CLWB */
ud = 0;
/* clwb (%rbx): */
asm volatile(".byte 0x66, 0x0f, 0xae, 0x33" : : "b" (&target));
- report_xfail("clwb", xfail, ud == 0);
+ if (host_has_clwb)
+ report("clwb", ud == 0);
+ else
+ report_xfail("clwb", xfail, ud == 0);
ud = 0;
/* clwb requires a memory operand, the following is NOT a valid
--
2.14.1
