From e05ee2994a9c188fc49a9ddf70b79ed7f1808e2f Mon Sep 17 00:00:00 2001 From: Zhao Liu Date: Thu, 6 Jun 2024 22:08:58 +0800 Subject: [PATCH] i386/apic: Add hint on boot failure because of disabling x2APIC MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Currently, the Q35 supports up to 4096 vCPUs (since v9.0), but for TCG cases, if x2APIC is not actively enabled to boot more than 255 vCPUs ( e.g., qemu-system-i386 -M pc-q35-9.0 -smp 666), the following error is reported: Unexpected error in apic_common_set_id() at ../hw/intc/apic_common.c:449: qemu-system-i386: APIC ID 255 requires x2APIC feature in CPU Aborted (core dumped) This error can be resolved by setting x2apic=on in -cpu. In order to better help users deal with this scenario, add the error hint to instruct users on how to enable the x2apic feature. Then, the error report becomes the following: Unexpected error in apic_common_set_id() at ../hw/intc/apic_common.c:448: qemu-system-i386: APIC ID 255 requires x2APIC feature in CPU Try x2apic=on in -cpu. Aborted (core dumped) Note since @errp is &error_abort, error_append_hint() can't be applied on @errp. And in order to separate the exact error message from the (perhaps effectively) hint, adding a hint via error_append_hint() is also necessary. Therefore, introduce @local_error in apic_common_set_id() to handle both the error message and the error hint. Suggested-by: Philippe Mathieu-Daudé Signed-off-by: Zhao Liu Message-Id: <20240606140858.2157106-1-zhao1.liu@intel.com> Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/intc/apic_common.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/hw/intc/apic_common.c b/hw/intc/apic_common.c index d8fc1e2815..c13cdd7994 100644 --- a/hw/intc/apic_common.c +++ b/hw/intc/apic_common.c @@ -433,6 +433,7 @@ static void apic_common_set_id(Object *obj, Visitor *v, const char *name, APICCommonState *s = APIC_COMMON(obj); DeviceState *dev = DEVICE(obj); uint32_t value; + Error *local_err = NULL; if (dev->realized) { qdev_prop_set_after_realize(dev, name, errp); @@ -444,7 +445,11 @@ static void apic_common_set_id(Object *obj, Visitor *v, const char *name, } if (value >= 255 && !cpu_has_x2apic_feature(&s->cpu->env)) { - error_setg(errp, "APIC ID %d requires x2APIC feature in CPU", value); + error_setg(&local_err, + "APIC ID %d requires x2APIC feature in CPU", + value); + error_append_hint(&local_err, "Try x2apic=on in -cpu.\n"); + error_propagate(errp, local_err); return; }