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spapr: introduce a fixed IRQ number space

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This proposal introduces a new IRQ number space layout using static
numbers for all devices, depending on a device index, and a bitmap
allocator for the MSI IRQ numbers which are negotiated by the guest at
runtime.

As the VIO device model does not have a device index but a "reg"
property, we introduce a formula to compute an IRQ number from a "reg"
value. It should minimize most of the collisions.

The previous layout is kept in pre-3.1 machines raising the
'legacy_irq_allocation' machine class flag.

Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This commit is contained in:
Cédric Le Goater 2018-07-30 16:11:32 +02:00 • committed by David Gibson
parent d45360d93d
commit 82cffa2eb2
8 changed files with 216 additions and 18 deletions
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56
hw/ppc/spapr_irq.c Normal file
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/*
* QEMU PowerPC sPAPR IRQ interface
*
* Copyright (c) 2018, IBM Corporation.
*
* This code is licensed under the GPL version 2 or later. See the
* COPYING file in the top-level directory.
*/
#include "qemu/osdep.h"
#include "qemu/log.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "hw/ppc/spapr.h"
#include "hw/ppc/xics.h"
void spapr_irq_msi_init(sPAPRMachineState *spapr, uint32_t nr_msis)
{
spapr->irq_map_nr = nr_msis;
spapr->irq_map = bitmap_new(spapr->irq_map_nr);
}
int spapr_irq_msi_alloc(sPAPRMachineState *spapr, uint32_t num, bool align,
Error **errp)
{
int irq;
/*
* The 'align_mask' parameter of bitmap_find_next_zero_area()
* should be one less than a power of 2; 0 means no
* alignment. Adapt the 'align' value of the former allocator
* to fit the requirements of bitmap_find_next_zero_area()
*/
align -= 1;
irq = bitmap_find_next_zero_area(spapr->irq_map, spapr->irq_map_nr, 0, num,
align);
if (irq == spapr->irq_map_nr) {
error_setg(errp, "can't find a free %d-IRQ block", num);
return -1;
}
bitmap_set(spapr->irq_map, irq, num);
return irq + SPAPR_IRQ_MSI;
}
void spapr_irq_msi_free(sPAPRMachineState *spapr, int irq, uint32_t num)
{
bitmap_clear(spapr->irq_map, irq - SPAPR_IRQ_MSI, num);
}
void spapr_irq_msi_reset(sPAPRMachineState *spapr)
{
bitmap_clear(spapr->irq_map, 0, spapr->irq_map_nr);
}