From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> According to TDX module spec version 344425-002US [1], VMM can inject virtual interrupt only via posted interrupt and VMM can't get TDEXIT on guest EOI to virtual x2APIC. Because posted interrupt is edge-trigger and VMM needs to hook guest EOI to re-inject level-triggered interrupt if the level still active, level-trigger isn't supported for TD Guest VM. Prevent trigger mode from setting to be level trigger with warning. Without this guard, qemu can result in unexpected behavior later. [1] https://software.intel.com/content/dam/develop/external/us/en/documents/tdx-module-1eas-v0.85.039.pdf Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx> --- hw/intc/ioapic.c | 20 ++++++++++++++++++++ hw/intc/ioapic_common.c | 27 +++++++++++++++++++++++++++ include/hw/i386/ioapic_internal.h | 1 + 3 files changed, 48 insertions(+) diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c index 264262959d..6d61744961 100644 --- a/hw/intc/ioapic.c +++ b/hw/intc/ioapic.c @@ -364,6 +364,23 @@ ioapic_fix_edge_remote_irr(uint64_t *entry) } } +static inline void +ioapic_fix_level_trigger_unsupported(uint64_t *entry) +{ + if ((*entry & IOAPIC_LVT_TRIGGER_MODE) != + IOAPIC_TRIGGER_EDGE << IOAPIC_LVT_TRIGGER_MODE_SHIFT) { + /* + * ignore a request for level trigger because + * level trigger requires eoi intercept to re-inject + * interrupt when the level is still active. + */ + warn_report_once("attempting to set level-trigger mode " + "while eoi intercept isn't supported"); + *entry &= ~IOAPIC_LVT_TRIGGER_MODE; + *entry |= IOAPIC_TRIGGER_EDGE << IOAPIC_LVT_TRIGGER_MODE_SHIFT; + } +} + static void ioapic_mem_write(void *opaque, hwaddr addr, uint64_t val, unsigned int size) @@ -404,6 +421,9 @@ ioapic_mem_write(void *opaque, hwaddr addr, uint64_t val, s->ioredtbl[index] &= IOAPIC_RW_BITS; s->ioredtbl[index] |= ro_bits; s->irq_eoi[index] = 0; + if (s->level_trigger_unsupported) { + ioapic_fix_level_trigger_unsupported(&s->ioredtbl[index]); + } ioapic_fix_edge_remote_irr(&s->ioredtbl[index]); ioapic_service(s); } diff --git a/hw/intc/ioapic_common.c b/hw/intc/ioapic_common.c index 3cccfc1556..07ee142470 100644 --- a/hw/intc/ioapic_common.c +++ b/hw/intc/ioapic_common.c @@ -150,6 +150,32 @@ static int ioapic_dispatch_post_load(void *opaque, int version_id) return 0; } +static bool ioapic_common_get_level_trigger_unsupported(Object *obj, + Error **errp) +{ + IOAPICCommonState *s = IOAPIC_COMMON(obj); + return s->level_trigger_unsupported; +} + +static void ioapic_common_set_level_trigger_unsupported(Object *obj, bool value, + Error **errp) +{ + DeviceState *dev = DEVICE(obj); + IOAPICCommonState *s = IOAPIC_COMMON(obj); + /* only disabling before realize is allowed */ + assert(!dev->realized); + assert(!s->level_trigger_unsupported); + s->level_trigger_unsupported = value; +} + +static void ioapic_common_init(Object *obj) +{ + object_property_add_bool(obj, "level_trigger_unsupported", + ioapic_common_get_level_trigger_unsupported, + ioapic_common_set_level_trigger_unsupported); + +} + static void ioapic_common_realize(DeviceState *dev, Error **errp) { IOAPICCommonState *s = IOAPIC_COMMON(dev); @@ -207,6 +233,7 @@ static const TypeInfo ioapic_common_type = { .name = TYPE_IOAPIC_COMMON, .parent = TYPE_SYS_BUS_DEVICE, .instance_size = sizeof(IOAPICCommonState), + .instance_init = ioapic_common_init, .class_size = sizeof(IOAPICCommonClass), .class_init = ioapic_common_class_init, .abstract = true, diff --git a/include/hw/i386/ioapic_internal.h b/include/hw/i386/ioapic_internal.h index 021e715f11..20f2fc7897 100644 --- a/include/hw/i386/ioapic_internal.h +++ b/include/hw/i386/ioapic_internal.h @@ -103,6 +103,7 @@ struct IOAPICCommonState { uint32_t irr; uint64_t ioredtbl[IOAPIC_NUM_PINS]; Notifier machine_done; + bool level_trigger_unsupported; uint8_t version; uint64_t irq_count[IOAPIC_NUM_PINS]; int irq_level[IOAPIC_NUM_PINS]; -- 2.25.1
