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[Qemu-devel] [PATCH v6 18/26] ioapic: clear remote irr bit for edge-trig
From: |
Peter Xu |
Subject: |
[Qemu-devel] [PATCH v6 18/26] ioapic: clear remote irr bit for edge-triggered interrupts |
Date: |
Thu, 5 May 2016 11:25:53 +0800 |
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>
---
hw/intc/ioapic.c | 29 +++++++++++++++++++++++++++++
1 file changed, 29 insertions(+)
diff --git a/hw/intc/ioapic.c b/hw/intc/ioapic.c
index d7ebb5c..ce06954 100644
--- a/hw/intc/ioapic.c
+++ b/hw/intc/ioapic.c
@@ -281,6 +281,34 @@ 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)
@@ -318,6 +346,7 @@ 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);
}
}
--
2.4.11
- Re: [Qemu-devel] [PATCH v6 08/26] intel_iommu: provide helper function vtd_get_iommu, (continued)
- [Qemu-devel] [PATCH v6 09/26] intel_iommu: add IR translation faults defines, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 10/26] intel_iommu: Add support for PCI MSI remap, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 11/26] q35: ioapic: add support for emulated IOAPIC IR, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 12/26] ioapic: introduce ioapic_entry_parse() helper, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 13/26] intel_iommu: add support for split irqchip, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 14/26] q35: add "intremap" parameter to enable IR, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 15/26] intel_iommu: introduce IEC notifiers, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 16/26] ioapic: register VT-d IEC invalidate notifier, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 17/26] ioapic: keep RO bits for IOAPIC entry, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 18/26] ioapic: clear remote irr bit for edge-triggered interrupts,
Peter Xu <=
- [Qemu-devel] [PATCH v6 19/26] intel_iommu: Add support for Extended Interrupt Mode, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 20/26] intel_iommu: add SID validation for IR, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 21/26] x86-iommu: introduce parent class, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 22/26] x86-iommu: replace existing VT-d hooks into X86 ones, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 23/26] kvm-irqchip: simplify kvm_irqchip_add_msi_route, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 25/26] kvm-irqchip: x86: add msi route notify fn, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 26/26] kvm-irqchip: do explicit commit when update irq, Peter Xu, 2016/05/04
- [Qemu-devel] [PATCH v6 24/26] kvm-irqchip: i386: add hook for add/remove virq, Peter Xu, 2016/05/04