On 08/14/2015 01:58 PM, Eric Auger wrote:
> On 07/10/2015 04:21 PM, Andre Przywara wrote:
>> The LPI configuration and pending tables of the GICv3 LPIs are held
>> in tables in (guest) memory. To achieve reasonable performance, we
>> cache this data in our own data structures, so we need to sync those
>> two views from time to time. This behaviour is well described in the
>> GICv3 spec and is also exercised by hardware, so the sync points are
>> well known.
>>
>> Provide functions that read the guest memory and store the
>> information from the configuration and pending tables in the kernel.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
>> ---
> would help to have change log between v1 -> v2 (valid for the whole series)
>> include/kvm/arm_vgic.h | 2 +
>> virt/kvm/arm/its-emul.c | 124 ++++++++++++++++++++++++++++++++++++++++++++++++
>> virt/kvm/arm/its-emul.h | 3 ++
>> 3 files changed, 129 insertions(+)
>>
>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>> index 2a67a10..323c33a 100644
>> --- a/include/kvm/arm_vgic.h
>> +++ b/include/kvm/arm_vgic.h
>> @@ -167,6 +167,8 @@ struct vgic_its {
>> int cwriter;
>> struct list_head device_list;
>> struct list_head collection_list;
>> + /* memory used for buffering guest's memory */
>> + void *buffer_page;
>> };
>>
>> struct vgic_dist {
>> diff --git a/virt/kvm/arm/its-emul.c b/virt/kvm/arm/its-emul.c
>> index b9c40d7..05245cb 100644
>> --- a/virt/kvm/arm/its-emul.c
>> +++ b/virt/kvm/arm/its-emul.c
>> @@ -50,6 +50,7 @@ struct its_itte {
>> struct its_collection *collection;
>> u32 lpi;
>> u32 event_id;
>> + u8 priority;
>> bool enabled;
>> unsigned long *pending;
>> };
>> @@ -70,8 +71,124 @@ static struct its_itte *find_itte_by_lpi(struct kvm *kvm, int lpi)
>> return NULL;
>> }
>>
>> +#define LPI_PROP_ENABLE_BIT(p) ((p) & LPI_PROP_ENABLED)
>> +#define LPI_PROP_PRIORITY(p) ((p) & 0xfc)
>> +
>> +/* stores the priority and enable bit for a given LPI */
>> +static void update_lpi_config(struct kvm *kvm, struct its_itte *itte, u8 prop)
>> +{
>> + itte->priority = LPI_PROP_PRIORITY(prop);
>> + itte->enabled = LPI_PROP_ENABLE_BIT(prop);
>> +}
>> +
>> +#define GIC_LPI_OFFSET 8192
>> +
>> +/* We scan the table in chunks the size of the smallest page size */
> 4kB chunks?
>> +#define CHUNK_SIZE 4096U
>> +
>> #define BASER_BASE_ADDRESS(x) ((x) & 0xfffffffff000ULL)
>>
>> +static int nr_idbits_propbase(u64 propbaser)
>> +{
>> + int nr_idbits = (1U << (propbaser & 0x1f)) + 1;
>> +
>> + return max(nr_idbits, INTERRUPT_ID_BITS_ITS);
>> +}
>> +
>> +/*
>> + * Scan the whole LPI configuration table and put the LPI configuration
>> + * data in our own data structures. This relies on the LPI being
>> + * mapped before.
>> + */
>> +static bool its_update_lpis_configuration(struct kvm *kvm)
>> +{
>> + struct vgic_dist *dist = &kvm->arch.vgic;
>> + u8 *prop = dist->its.buffer_page;
>> + u32 tsize;
>> + gpa_t propbase;
>> + int lpi = GIC_LPI_OFFSET;
>> + struct its_itte *itte;
>> + struct its_device *device;
>> + int ret;
>> +
>> + propbase = BASER_BASE_ADDRESS(dist->propbaser);
>> + tsize = nr_idbits_propbase(dist->propbaser);
>> +
>> + while (tsize > 0) {
>> + int chunksize = min(tsize, CHUNK_SIZE);
>> +
>> + ret = kvm_read_guest(kvm, propbase, prop, chunksize);
> I think you still have the spin_lock issue since if my understanding is
> correct this is called from
> vgic_handle_mmio_access/vcall_range_handler/gic_enable_lpis
> where vgic_handle_mmio_access. Or does it take another path?
>
> Shouldn't we create a new kvm_io_device to avoid holding the dist lock?
Sorry I forgot it was the case already. But currently we always register
the same io ops (registration entry point being
vgic_register_kvm_io_dev) and maybe we should have separate dispatcher
function for dist, redit and its?
Eric
>
> Eric
>> + if (ret)
>> + return false;
>> +
>> + spin_lock(&dist->its.lock);
>> + /*
>> + * Updating the status for all allocated LPIs. We catch
>> + * those LPIs that get disabled. We really don't care
>> + * about unmapped LPIs, as they need to be updated
>> + * later manually anyway once they get mapped.
>> + */
>> + for_each_lpi(device, itte, kvm) {
>> + if (itte->lpi < lpi || itte->lpi >= lpi + chunksize)
>> + continue;
>> +
>> + update_lpi_config(kvm, itte, prop[itte->lpi - lpi]);
>> + }
>> + spin_unlock(&dist->its.lock);
>> + tsize -= chunksize;
>> + lpi += chunksize;
>> + propbase += chunksize;
>> + }
>> +
>> + return true;
>> +}
>> +
>> +/*
>> + * Scan the whole LPI pending table and sync the pending bit in there
>> + * with our own data structures. This relies on the LPI being
>> + * mapped before.
>> + */
>> +static bool its_sync_lpi_pending_table(struct kvm_vcpu *vcpu)
>> +{
>> + struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
>> + unsigned long *pendmask = dist->its.buffer_page;
>> + u32 nr_lpis = VITS_NR_LPIS;
>> + gpa_t pendbase;
>> + int lpi = 0;
>> + struct its_itte *itte;
>> + struct its_device *device;
>> + int ret;
>> + int lpi_bit, nr_bits;
>> +
>> + pendbase = BASER_BASE_ADDRESS(dist->pendbaser[vcpu->vcpu_id]);
>> +
>> + while (nr_lpis > 0) {
>> + nr_bits = min(nr_lpis, CHUNK_SIZE * 8);
>> +
>> + ret = kvm_read_guest(vcpu->kvm, pendbase, pendmask,
>> + nr_bits / 8);
>> + if (ret)
>> + return false;
>> +
>> + spin_lock(&dist->its.lock);
>> + for_each_lpi(device, itte, vcpu->kvm) {
>> + lpi_bit = itte->lpi - lpi;
>> + if (lpi_bit < 0 || lpi_bit >= nr_bits)
>> + continue;
>> + if (test_bit(lpi_bit, pendmask))
>> + __set_bit(vcpu->vcpu_id, itte->pending);
>> + else
>> + __clear_bit(vcpu->vcpu_id, itte->pending);
>> + }
>> + spin_unlock(&dist->its.lock);
>> + nr_lpis -= nr_bits;
>> + lpi += nr_bits;
>> + pendbase += nr_bits / 8;
>> + }
>> +
>> + return true;
>> +}
>> +
>> /* The distributor lock is held by the VGIC MMIO handler. */
>> static bool handle_mmio_misc_gits(struct kvm_vcpu *vcpu,
>> struct kvm_exit_mmio *mmio,
>> @@ -389,6 +506,8 @@ static const struct vgic_io_range vgicv3_its_ranges[] = {
>> /* This is called on setting the LPI enable bit in the redistributor. */
>> void vgic_enable_lpis(struct kvm_vcpu *vcpu)
>> {
>> + its_update_lpis_configuration(vcpu->kvm);
>> + its_sync_lpi_pending_table(vcpu);
>> }
>>
>> int vits_init(struct kvm *kvm)
>> @@ -400,6 +519,10 @@ int vits_init(struct kvm *kvm)
>> if (!dist->pendbaser)
>> return -ENOMEM;
>>
>> + its->buffer_page = kmalloc(CHUNK_SIZE, GFP_KERNEL);
>> + if (!its->buffer_page)
>> + return -ENOMEM;
>> +
>> spin_lock_init(&its->lock);
>>
>> INIT_LIST_HEAD(&its->device_list);
>> @@ -442,6 +565,7 @@ void vits_destroy(struct kvm *kvm)
>> kfree(container_of(cur, struct its_collection, coll_list));
>> }
>>
>> + kfree(its->buffer_page);
>> kfree(dist->pendbaser);
>>
>> its->enabled = false;
>> diff --git a/virt/kvm/arm/its-emul.h b/virt/kvm/arm/its-emul.h
>> index cc5d5ff..cbc3877 100644
>> --- a/virt/kvm/arm/its-emul.h
>> +++ b/virt/kvm/arm/its-emul.h
>> @@ -29,6 +29,9 @@
>>
>> #include "vgic.h"
>>
>> +#define INTERRUPT_ID_BITS_ITS 16
>> +#define VITS_NR_LPIS (1U << INTERRUPT_ID_BITS_ITS)
>> +
>> void vgic_enable_lpis(struct kvm_vcpu *vcpu);
>> int vits_init(struct kvm *kvm);
>> void vits_destroy(struct kvm *kvm);
>>
>
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