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[Qemu-devel] [PULL 07/24] ioapic: clear remote irr bit for edge-triggere
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 07/24] ioapic: clear remote irr bit for edge-triggered interrupts |
Date: |
Mon, 23 May 2016 17:09:42 +0200 |
From: Peter Xu <address@hidden>
This is to better emulate IOAPIC version 0x1X hardware. Linux kernel
leveraged this "feature" to do explicit EOI since EOI register is still
not introduced at that time. This will also fix the issue that level
triggered interrupts failed to work when IR enabled (tested with Linux
kernel version 4.5).
Reviewed-by: Radim Krčmář <address@hidden>
Signed-off-by: Peter Xu <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
hw/intc/ioapic.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
index c27ee83..273bb08 100644
--- a/hw/intc/ioapic.c
+++ b/hw/intc/ioapic.c
@@ -255,6 +255,34 @@ ioapic_mem_read(void *opaque, hwaddr addr, unsigned int
size)
return val;
}
+/*
+ * This is to satisfy the hack in Linux kernel. One hack of it is to
+ * simulate clearing the Remote IRR bit of IOAPIC entry using the
+ * following:
+ *
+ * "For IO-APIC's with EOI register, we use that to do an explicit EOI.
+ * Otherwise, we simulate the EOI message manually by changing the trigger
+ * mode to edge and then back to level, with RTE being masked during
+ * this."
+ *
+ * (See linux kernel __eoi_ioapic_pin() comment in commit c0205701)
+ *
+ * This is based on the assumption that, Remote IRR bit will be
+ * cleared by IOAPIC hardware when configured as edge-triggered
+ * interrupts.
+ *
+ * Without this, level-triggered interrupts in IR mode might fail to
+ * work correctly.
+ */
+static inline void
+ioapic_fix_edge_remote_irr(uint64_t *entry)
+{
+ if (!(*entry & IOAPIC_LVT_TRIGGER_MODE)) {
+ /* Edge-triggered interrupts, make sure remote IRR is zero */
+ *entry &= ~((uint64_t)IOAPIC_LVT_REMOTE_IRR);
+ }
+}
+
static void
ioapic_mem_write(void *opaque, hwaddr addr, uint64_t val,
unsigned int size)
@@ -292,6 +320,7 @@ ioapic_mem_write(void *opaque, hwaddr addr, uint64_t val,
/* restore RO bits */
s->ioredtbl[index] &= IOAPIC_RW_BITS;
s->ioredtbl[index] |= ro_bits;
+ ioapic_fix_edge_remote_irr(&s->ioredtbl[index]);
ioapic_service(s);
}
}
--
1.8.3.1
- [Qemu-devel] [PULL 00/24] Misc patches for 2016-05-23, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 03/24] i386: kvmvapic: initialise imm32 variable, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 06/24] ioapic: keep RO bits for IOAPIC entry, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 05/24] target-i386: key sfence availability on CPUID_SSE, not CPUID_SSE2, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 09/24] memory: drop find_ram_block(), Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 08/24] vl: change runstate only if new state is different from current state, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 13/24] memory: remove unnecessary masking of MemoryRegion ram_addr, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 07/24] ioapic: clear remote irr bit for edge-triggered interrupts,
Paolo Bonzini <=
- [Qemu-devel] [PULL 01/24] exec.c: Ensure right alignment also for file backed ram, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 02/24] docs/atomics.txt: Update pointer to linux macro, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 10/24] exec: adjust rcu_read_lock requirement, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 18/24] esp: check command buffer length before write(CVE-2016-4439), Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 04/24] configure: Allow builds with extra warnings, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 15/24] Remove config-devices.mak on 'make clean', Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 14/24] cpus.c: Use pthread_sigmask() rather than sigprocmask(), Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 23/24] nmi: remove x86 specific nmi handling, Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 19/24] esp: check dma length before reading scsi command(CVE-2016-4441), Paolo Bonzini, 2016/05/23
- [Qemu-devel] [PULL 12/24] memory: Drop FlatRange.romd_mode, Paolo Bonzini, 2016/05/23