On 2012-11-21 07:02, Liu Ping Fan wrote:
> From: Liu Ping Fan <pingf...@linux.vnet.ibm.com>
>
> Using irqfd, so we can avoid switch between kernel and user when
> VMs interrupts each other.
>
> Signed-off-by: Liu Ping Fan <pingf...@linux.vnet.ibm.com>
> ---
> hw/ivshmem.c | 48 +++++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 47 insertions(+), 1 deletions(-)
>
> diff --git a/hw/ivshmem.c b/hw/ivshmem.c
> index f6dbb21..81c7354 100644
> --- a/hw/ivshmem.c
> +++ b/hw/ivshmem.c
> @@ -19,6 +19,7 @@
> #include "hw.h"
> #include "pc.h"
> #include "pci.h"
> +#include "msi.h"
> #include "msix.h"
> #include "kvm.h"
> #include "migration.h"
> @@ -54,6 +55,11 @@ typedef struct EventfdEntry {
> int vector;
> } EventfdEntry;
>
> +typedef struct IrqfdEntry {
> + int virq;
> + bool used;
used = (virq != -1), so it should be redundant, and you can reduce
IrqfdEntry to a plain int holding the virq.
> +} IrqfdEntry;
> +
> typedef struct IVShmemState {
> PCIDevice dev;
> uint32_t intrmask;
> @@ -83,6 +89,8 @@ typedef struct IVShmemState {
> uint32_t vectors;
> uint32_t features;
> EventfdEntry *eventfd_table;
> + IrqfdEntry *vector_irqfd;
> + bool irqfd_enable;
>
> Error *migration_blocker;
>
> @@ -632,6 +640,38 @@ static void ivshmem_write_config(PCIDevice *pci_dev,
> uint32_t address,
> msix_write_config(pci_dev, address, val, len);
> }
>
> +static int ivshmem_vector_use(PCIDevice *dev, unsigned vector,
> + MSIMessage msg)
> +{
> + IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
> + int virq;
> + EventNotifier *n = &s->peers[s->vm_id].eventfds[vector];
> +
> + virq = kvm_irqchip_add_msi_route(kvm_state, msg);
> + if (virq >= 0 && kvm_irqchip_add_irqfd_notifier(kvm_state, n, virq) >=
> 0) {
> + s->vector_irqfd[vector].virq = virq;
> + s->vector_irqfd[vector].used = true;
> + qemu_chr_add_handlers(s->eventfd_chr[vector], NULL, NULL, NULL,
> NULL);
> + } else if (virq >= 0) {
> + kvm_irqchip_release_virq(kvm_state, virq);
> + }
> + return 0;
You drop the errors here. Better refactor the code to a scheme like this:
err = service();
if (err) {
roll_back();
return err;
/* or: goto roll_back_... */
}
> +}
> +
> +static void ivshmem_vector_release(PCIDevice *dev, unsigned vector)
> +{
> + IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
> + EventNotifier *n = &s->peers[s->vm_id].eventfds[vector];
> + int virq = s->vector_irqfd[vector].virq;
> +
> + if (s->vector_irqfd[vector].used) {
> + kvm_irqchip_remove_irqfd_notifier(kvm_state, n, virq);
> + kvm_irqchip_release_virq(kvm_state, virq);
> + s->vector_irqfd[vector].virq = -1;
> + s->vector_irqfd[vector].used = false;
> + }
> +}
> +
> static int pci_ivshmem_init(PCIDevice *dev)
> {
> IVShmemState *s = DO_UPCAST(IVShmemState, dev, dev);
> @@ -759,7 +799,13 @@ static int pci_ivshmem_init(PCIDevice *dev)
> }
>
> s->dev.config_write = ivshmem_write_config;
> -
> + if (kvm_gsi_routing_enabled()) {
> + s->irqfd_enable = msix_set_vector_notifiers(dev, ivshmem_vector_use,
> + ivshmem_vector_release) >= 0 ? true : false;
> + if (s->irqfd_enable) {
> + s->vector_irqfd = g_new0(IrqfdEntry, s->vectors);
Conceptually, msix_set_vector_notifiers can already call
ivshmem_vector_use, so this initialization would come too late. Doesn't
happen here as MSI-X is still off during device init. However, just
perform vector_irqfd allocation unconditionally before the registration.
And where do you free it again...?
> + }
> + }
> return 0;
> }
>
>
Jan
--
Siemens AG, Corporate Technology, CT RTC ITP SDP-DE
Corporate Competence Center Embedded Linux
