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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 17/22] vixen: setup infrastructure to receive event channel notifications
On Sat, Jan 06, 2018 at 02:54:32PM -0800, Anthony Liguori wrote:
> From: Anthony Liguori <aliguori@xxxxxxxxxx>
>
> This patch registers an interrupt handler using either an INTx
> interrupt from the platform PCI device, CALLBACK_IRQ vector
> delivery, or evtchn_upcall_vector depending on what the parent
> hypervisor supports.
>
> The event channel polling code comes from Linux but uses the
> internal infrastructure for delivery.
>
> Finally, this infrastructure has to be initialized per-VCPU so
> hook the appropriate place for that.
>
> Signed-off-by: KarimAllah Ahmed <karahmed@xxxxxxxxx>
> Signed-off-by: Jan H. Schönherr <jschoenh@xxxxxxxxx>
> Signed-off-by: Anthony Liguori <aliguori@xxxxxxxxxx>
> ---
> xen/arch/x86/domain.c | 3 +
> xen/arch/x86/guest/vixen.c | 264
> ++++++++++++++++++++++++++++++++++++++
> xen/arch/x86/setup.c | 3 +
> xen/include/asm-x86/guest/vixen.h | 6 +
> 4 files changed, 276 insertions(+)
>
> diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
> index da1bf1a..3e9c5be 100644
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -1147,6 +1147,9 @@ int arch_set_info_guest(
>
> update_cr3(v);
>
> + if ( is_vixen() )
> + vixen_vcpu_initialize(v);
> +
> out:
> if ( flags & VGCF_online )
> clear_bit(_VPF_down, &v->pause_flags);
> diff --git a/xen/arch/x86/guest/vixen.c b/xen/arch/x86/guest/vixen.c
> index 1816ece..76d9638 100644
> --- a/xen/arch/x86/guest/vixen.c
> +++ b/xen/arch/x86/guest/vixen.c
> @@ -21,10 +21,16 @@
>
> #include <asm/guest/vixen.h>
> #include <public/version.h>
> +#include <xen/event.h>
> +#include <asm/apic.h>
>
> static int in_vixen;
> static uint8_t global_si_data[4 << 10] __attribute__((aligned(4096)));
> static shared_info_t *global_si = (void *)global_si_data;
> +static bool vixen_per_cpu_notifications = true;
> +static uint8_t vixen_evtchn_vector;
> +static bool vixen_needs_apic_ack = true;
> +struct irqaction vixen_irqaction;
>
> void __init init_vixen(void)
> {
> @@ -94,3 +100,261 @@ u64 vixen_get_cpu_freq(void)
> return imm >> time.tsc_shift;
> }
> }
> +
> +/*
> + * Make a bitmask (i.e. unsigned long *) of a xen_ulong_t
> + * array. Primarily to avoid long lines (hence the terse name).
> + */
> +#define BM(x) (unsigned long *)(x)
> +/* Find the first set bit in a evtchn mask */
> +#define EVTCHN_FIRST_BIT(w) find_first_bit(BM(&(w)), BITS_PER_XEN_ULONG)
> +
> +/*
> + * Mask out the i least significant bits of w
> + */
> +#define MASK_LSBS(w, i) (w & ((~((xen_ulong_t)0UL)) << i))
> +
> +static DEFINE_PER_CPU(unsigned int, current_word_idx);
> +static DEFINE_PER_CPU(unsigned int, current_bit_idx);
> +
> +static inline xen_ulong_t active_evtchns(unsigned int cpu,
> + shared_info_t *sh,
> + unsigned int idx)
> +{
> + return sh->native.evtchn_pending[idx] &
> + ~sh->native.evtchn_mask[idx];
> +}
> +
> +static void vixen_evtchn_poll_one(size_t cpu)
> +{
All this seems overly complicated, specially taking into account that
vixen itself doesn't execute almost any code for each interrupt, since
they are forwarded to the guest. IMHO you could have a simpler event
channel loop without loosing much performance or fairness (but I
haven't done much tests regarding that, so I could be wrong).
> + shared_info_t *s = global_si;
> + struct vcpu_info *vcpu_info = &s->native.vcpu_info[cpu];
> + xen_ulong_t pending_words;
> + xen_ulong_t pending_bits;
> + int start_word_idx, start_bit_idx;
> + int word_idx, bit_idx, i;
> +
> + /*
> + * Master flag must be cleared /before/ clearing
> + * selector flag. xchg_xen_ulong must contain an
> + * appropriate barrier.
> + */
> + pending_words = xchg(&vcpu_info->evtchn_pending_sel, 0);
> +
> + start_word_idx = this_cpu(current_word_idx);
> + start_bit_idx = this_cpu(current_bit_idx);
> +
> + word_idx = start_word_idx;
> +
> + for (i = 0; pending_words != 0; i++) {
> + xen_ulong_t words;
> +
> + words = MASK_LSBS(pending_words, word_idx);
> +
> + /*
> + * If we masked out all events, wrap to beginning.
> + */
> + if (words == 0) {
> + word_idx = 0;
> + bit_idx = 0;
> + continue;
> + }
> + word_idx = EVTCHN_FIRST_BIT(words);
> +
> + pending_bits = active_evtchns(cpu, s, word_idx);
> + bit_idx = 0; /* usually scan entire word from start */
> + /*
> + * We scan the starting word in two parts.
> + *
> + * 1st time: start in the middle, scanning the
> + * upper bits.
> + *
> + * 2nd time: scan the whole word (not just the
> + * parts skipped in the first pass) -- if an
> + * event in the previously scanned bits is
> + * pending again it would just be scanned on
> + * the next loop anyway.
> + */
> + if (word_idx == start_word_idx) {
> + if (i == 0)
> + bit_idx = start_bit_idx;
> + }
> +
> + do {
> + struct evtchn *chn;
> + xen_ulong_t bits;
> + int port;
> +
> + bits = MASK_LSBS(pending_bits, bit_idx);
> +
> + /* If we masked out all events, move on. */
> + if (bits == 0)
> + break;
> +
> + bit_idx = EVTCHN_FIRST_BIT(bits);
> +
> + /* Process port. */
> + port = (word_idx * BITS_PER_XEN_ULONG) + bit_idx;
> +
> + chn = evtchn_from_port(hardware_domain, port);
> + clear_bit(port, s->native.evtchn_pending);
> + evtchn_port_set_pending(hardware_domain, chn->notify_vcpu_id,
> chn);
> +
> + bit_idx = (bit_idx + 1) % BITS_PER_XEN_ULONG;
> +
> + /* Next caller starts at last processed + 1 */
> + this_cpu(current_word_idx) = bit_idx ? word_idx : (word_idx+1) %
> BITS_PER_XEN_ULONG;
> + this_cpu(current_bit_idx) = bit_idx;
> + } while (bit_idx != 0);
> +
> + /* Scan start_l1i twice; all others once. */
> + if ((word_idx != start_word_idx) || (i != 0))
> + pending_words &= ~(1UL << word_idx);
> +
> + word_idx = (word_idx + 1) % BITS_PER_XEN_ULONG;
> + }
> +}
> +
> +static void vixen_upcall(int cpu)
> +{
> + shared_info_t *s = global_si;
> + struct vcpu_info *vcpu_info = &s->native.vcpu_info[cpu];
> +
> + do {
> + vcpu_info->evtchn_upcall_pending = 0;
> + vixen_evtchn_poll_one(cpu);
> + } while (vcpu_info->evtchn_upcall_pending);
> +}
> +
> +static void vixen_evtchn_notify(struct cpu_user_regs *regs)
> +{
> + if (vixen_needs_apic_ack)
> + ack_APIC_irq();
> +
> + vixen_upcall(smp_processor_id());
> +}
> +
> +static void vixen_interrupt(int irq, void *dev_id, struct cpu_user_regs
> *regs)
> +{
> + vixen_upcall(smp_processor_id());
> +}
> +
> +static int hvm_set_parameter(int idx, uint64_t value)
> +{
> + struct xen_hvm_param xhv;
> + int r;
> +
> + xhv.domid = DOMID_SELF;
> + xhv.index = idx;
> + xhv.value = value;
> + r = HYPERVISOR_hvm_op(HVMOP_set_param, &xhv);
> + if (r < 0) {
> + printk("Cannot set hvm parameter %d: %d!\n",
> + idx, r);
> + return r;
> + }
> + return r;
> +}
> +
> +void vixen_vcpu_initialize(struct vcpu *v)
> +{
> + struct xen_hvm_evtchn_upcall_vector upcall;
> + long rc;
> +
> + printk("VIXEN vcpu init VCPU%d\n", v->vcpu_id);
> +
> + vcpu_pin_override(v, v->vcpu_id);
> +
> + if (!vixen_needs_apic_ack)
> + return;
> +
> + printk("VIXEN vcpu init VCPU%d -- trying evtchn_upcall_vector\n",
> v->vcpu_id);
> +
> + upcall.vcpu = v->vcpu_id;
> + upcall.vector = vixen_evtchn_vector;
> + rc = HYPERVISOR_hvm_op(HVMOP_set_evtchn_upcall_vector, &upcall);
> + if ( rc )
> + {
> + struct xen_feature_info fi;
> +
> + printk("VIXEN vcpu init VCPU%d -- trying hvm_callback_vector\n",
> v->vcpu_id);
> +
> + fi.submap_idx = 0;
> + rc = HYPERVISOR_xen_version(XENVER_get_features, &fi);
> + if ( !rc )
> + {
> + rc = -EINVAL;
> + if ( fi.submap & (1 << XENFEAT_hvm_callback_vector) )
> + {
> + rc = hvm_set_parameter(HVM_PARAM_CALLBACK_IRQ,
> +
> ((uint64_t)HVM_PARAM_CALLBACK_TYPE_VECTOR << 56) | vixen_evtchn_vector);
> + }
> + if ( !rc )
> + vixen_needs_apic_ack = false;
> + }
> + }
> +
> + if ( rc )
> + {
> + int slot;
> +
> + vixen_per_cpu_notifications = false;
> +
> + printk("VIXEN vcpu init VCPU%d -- trying pci_intx_callback\n",
> v->vcpu_id);
> + for (slot = 2; slot < 32; slot++) {
Coding style for braces and missing spaces in the condition, here and
below.
> + uint16_t vendor, device;
> +
> + vendor = pci_conf_read16(0, 0, slot, 0, PCI_VENDOR_ID);
> + device = pci_conf_read16(0, 0, slot, 0, PCI_DEVICE_ID);
> +
> + if (vendor == 0x5853 && device == 0x0001) {
Those values should be made defines and documented somewhere.
Thanks, Roger.
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