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Re: [Qemu-devel] [PATCH] apic: Implement low-priority arbitration for IR
From: |
James Sullivan |
Subject: |
Re: [Qemu-devel] [PATCH] apic: Implement low-priority arbitration for IRQ delivery |
Date: |
Tue, 24 Mar 2015 13:16:00 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 |
Merging this into
<address@hidden>.
On 03/23/2015 04:26 PM, James Sullivan wrote:
> Currently, there is no arbitration among processors for low priority IRQ
> delivery. Implemented apic_get_arb_pri(), and added two new functions
> apic_compare_prio() and apic_lowest_prio() to support arbitration in
> apic_bus_deliver().
>
> Signed-off-by: James Sullivan <address@hidden>
> ---
> hw/intc/apic.c | 67
> ++++++++++++++++++++++++++++++++++++++++++----------------
> 1 file changed, 49 insertions(+), 18 deletions(-)
>
> diff --git a/hw/intc/apic.c b/hw/intc/apic.c
> index 0f97b47..47d2fb1 100644
> --- a/hw/intc/apic.c
> +++ b/hw/intc/apic.c
> @@ -38,6 +38,7 @@ static void apic_set_irq(APICCommonState *s, int
> vector_num, int trigger_mode);
> static void apic_update_irq(APICCommonState *s);
> static void apic_get_delivery_bitmask(uint32_t *deliver_bitmask,
> uint8_t dest, uint8_t dest_mode);
> +static int apic_get_arb_pri(APICCommonState *s);
>
> /* Find first bit starting from msb */
> static int apic_fls_bit(uint32_t value)
> @@ -199,6 +200,29 @@ static void apic_external_nmi(APICCommonState *s)
> apic_local_deliver(s, APIC_LVT_LINT1);
> }
>
> +static int apic_compare_prio(struct APICCommonState *cpu1,
> + struct APICCommonState *cpu2)
> +{
> + return apic_get_arb_pri(cpu1) - apic_get_arb_pri(cpu2);
> +}
> +
> +static struct APICCommonState *apic_lowest_prio(const uint32_t
> + *deliver_bitmask)
> +{
> + APICCommonState *lowest = NULL;
> + int i, d;
> +
> + for (i = 0; i < MAX_APIC_WORDS; i++) {
> + if (deliver_bitmask[i]) {
> + d = i * 32 + apic_ffs_bit(deliver_bitmask[i]);
> + if (!lowest || apic_compare_prio(local_apics[d], lowest) < 0) {
> + lowest = local_apics[d];
> + }
> + }
> + }
> + return lowest;
> +}
> +
> #define foreach_apic(apic, deliver_bitmask, code) \
> {\
> int __i, __j;\
> @@ -225,22 +249,10 @@ static void apic_bus_deliver(const uint32_t
> *deliver_bitmask,
>
> switch (delivery_mode) {
> case APIC_DM_LOWPRI:
> - /* XXX: search for focus processor, arbitration */
> - {
> - int i, d;
> - d = -1;
> - for(i = 0; i < MAX_APIC_WORDS; i++) {
> - if (deliver_bitmask[i]) {
> - d = i * 32 + apic_ffs_bit(deliver_bitmask[i]);
> - break;
> - }
> - }
> - if (d >= 0) {
> - apic_iter = local_apics[d];
> - if (apic_iter) {
> - apic_set_irq(apic_iter, vector_num, trigger_mode);
> - }
> - }
> + /* XXX: search for focus processor */
> + apic_iter = apic_lowest_prio(deliver_bitmask);
> + if (apic_iter) {
> + apic_set_irq(apic_iter , vector_num, trigger_mode);
> }
> return;
>
> @@ -336,8 +348,27 @@ static int apic_get_ppr(APICCommonState *s)
>
> static int apic_get_arb_pri(APICCommonState *s)
> {
> - /* XXX: arbitration */
> - return 0;
> + int tpr, isrv, irrv, apr;
> +
> + tpr = apic_get_tpr(s);
> + isrv = get_highest_priority_int(s->isr);
> + if (isrv < 0) {
> + isrv = 0;
> + }
> + isrv >>= 4;
> + irrv = get_highest_priority_int(s->irr);
> + if (irrv < 0) {
> + irrv = 0;
> + }
> + irrv >>= 4;
> +
> + if ((tpr >= irrv) && (tpr > isrv)) {
> + apr = s->tpr & 0xff;
> + } else {
> + apr = ((tpr & isrv) > irrv) ? (tpr & isrv) : irrv;
> + apr <<= 4;
> + }
> + return apr;
> }
>
>
>