[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [Qemu-ppc] [PATCH v2 2/2] spapr/irq: Only claim VALID interrupts at
From: |
Greg Kurz |
Subject: |
Re: [Qemu-ppc] [PATCH v2 2/2] spapr/irq: Only claim VALID interrupts at the KVM level |
Date: |
Wed, 11 Sep 2019 16:14:25 +0200 |
On Wed, 11 Sep 2019 15:39:37 +0200
Cédric Le Goater <address@hidden> wrote:
> A typical pseries VM with 16 vCPUs, one disk, one network adapater
> uses less than 100 interrupts but the whole IRQ number space of the
> QEMU machine is allocated at reset time and it is 8K wide. This is
> wasting a considerable amount of interrupt numbers in the global IRQ
> space which has 1M interrupts per socket on a POWER9.
>
> To optimise the HW resources, only request at the KVM level interrupts
> which have been claimed by the guest. This will help to increase the
> maximum number of VMs per system and also help supporting nested guests
> using the XIVE interrupt mode.
>
> Signed-off-by: Cédric Le Goater <address@hidden>
> ---
Reviewed-by: Greg Kurz <address@hidden>
> hw/intc/spapr_xive_kvm.c | 29 ++++++++++++++++++++++++++---
> hw/intc/xics_kvm.c | 8 ++++++++
> 2 files changed, 34 insertions(+), 3 deletions(-)
>
> diff --git a/hw/intc/spapr_xive_kvm.c b/hw/intc/spapr_xive_kvm.c
> index 17af4d19f54e..71b88d7797bc 100644
> --- a/hw/intc/spapr_xive_kvm.c
> +++ b/hw/intc/spapr_xive_kvm.c
> @@ -255,11 +255,16 @@ void kvmppc_xive_source_reset_one(XiveSource *xsrc, int
> srcno, Error **errp)
>
> static void kvmppc_xive_source_reset(XiveSource *xsrc, Error **errp)
> {
> + SpaprXive *xive = SPAPR_XIVE(xsrc->xive);
> int i;
>
> for (i = 0; i < xsrc->nr_irqs; i++) {
> Error *local_err = NULL;
>
> + if (!xive_eas_is_valid(&xive->eat[i])) {
> + continue;
> + }
> +
> kvmppc_xive_source_reset_one(xsrc, i, &local_err);
> if (local_err) {
> error_propagate(errp, local_err);
> @@ -328,11 +333,18 @@ uint64_t kvmppc_xive_esb_rw(XiveSource *xsrc, int
> srcno, uint32_t offset,
>
> static void kvmppc_xive_source_get_state(XiveSource *xsrc)
> {
> + SpaprXive *xive = SPAPR_XIVE(xsrc->xive);
> int i;
>
> for (i = 0; i < xsrc->nr_irqs; i++) {
> + uint8_t pq;
> +
> + if (!xive_eas_is_valid(&xive->eat[i])) {
> + continue;
> + }
> +
> /* Perform a load without side effect to retrieve the PQ bits */
> - uint8_t pq = xive_esb_read(xsrc, i, XIVE_ESB_GET);
> + pq = xive_esb_read(xsrc, i, XIVE_ESB_GET);
>
> /* and save PQ locally */
> xive_source_esb_set(xsrc, i, pq);
> @@ -521,9 +533,14 @@ static void kvmppc_xive_change_state_handler(void
> *opaque, int running,
> */
> if (running) {
> for (i = 0; i < xsrc->nr_irqs; i++) {
> - uint8_t pq = xive_source_esb_get(xsrc, i);
> + uint8_t pq;
> uint8_t old_pq;
>
> + if (!xive_eas_is_valid(&xive->eat[i])) {
> + continue;
> + }
> +
> + pq = xive_source_esb_get(xsrc, i);
> old_pq = xive_esb_read(xsrc, i, XIVE_ESB_SET_PQ_00 + (pq << 8));
>
> /*
> @@ -545,7 +562,13 @@ static void kvmppc_xive_change_state_handler(void
> *opaque, int running,
> * migration is in progress.
> */
> for (i = 0; i < xsrc->nr_irqs; i++) {
> - uint8_t pq = xive_esb_read(xsrc, i, XIVE_ESB_GET);
> + uint8_t pq;
> +
> + if (!xive_eas_is_valid(&xive->eat[i])) {
> + continue;
> + }
> +
> + pq = xive_esb_read(xsrc, i, XIVE_ESB_GET);
>
> /*
> * PQ is set to PENDING to possibly catch a triggered
> diff --git a/hw/intc/xics_kvm.c b/hw/intc/xics_kvm.c
> index a4d2e876cc5f..ba90d6dc966c 100644
> --- a/hw/intc/xics_kvm.c
> +++ b/hw/intc/xics_kvm.c
> @@ -190,6 +190,10 @@ void ics_get_kvm_state(ICSState *ics)
> for (i = 0; i < ics->nr_irqs; i++) {
> ICSIRQState *irq = &ics->irqs[i];
>
> + if (ics_irq_free(ics, i)) {
> + continue;
> + }
> +
> kvm_device_access(kernel_xics_fd, KVM_DEV_XICS_GRP_SOURCES,
> i + ics->offset, &state, false, &error_fatal);
>
> @@ -301,6 +305,10 @@ int ics_set_kvm_state(ICSState *ics, Error **errp)
> Error *local_err = NULL;
> int ret;
>
> + if (ics_irq_free(ics, i)) {
> + continue;
> + }
> +
> ret = ics_set_kvm_state_one(ics, i, &local_err);
> if (ret < 0) {
> error_propagate(errp, local_err);