On 5/8/20 1:37 PM, Gerd Hoffmann wrote:
Read month register which should never have a value larger than 12.
In case the read returns 0xff assume the rtc isn't there.
Don't try to read the cpu count from cmos without rtc.
Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <phi...@redhat.com>
---
src/fw/paravirt.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/src/fw/paravirt.c b/src/fw/paravirt.c
index 3465f97ec0b0..e76fa65d87a0 100644
--- a/src/fw/paravirt.c
+++ b/src/fw/paravirt.c
@@ -447,6 +447,11 @@ qemu_get_romfile_key(struct romfile_s *file)
return qfile->select;
}
+static int rtc_present(void)
+{
+ return rtc_read(CMOS_RTC_MONTH) != 0xff;
+}
+
u16
qemu_get_present_cpus_count(void)
{
@@ -454,9 +459,11 @@ qemu_get_present_cpus_count(void)
if (qemu_cfg_enabled()) {
qemu_cfg_read_entry(&smp_count, QEMU_CFG_NB_CPUS, sizeof(smp_count));
}
- u16 cmos_cpu_count = rtc_read(CMOS_BIOS_SMP_COUNT) + 1;
- if (smp_count < cmos_cpu_count) {
- smp_count = cmos_cpu_count;
+ if (rtc_present()) {
+ u16 cmos_cpu_count = rtc_read(CMOS_BIOS_SMP_COUNT) + 1;
+ if (smp_count < cmos_cpu_count) {
+ smp_count = cmos_cpu_count;
+ }
}
return smp_count;
}
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