[RFC PATCH 1/5] arm/arm64: KVM: vgic: switch to dynamic allocation
Christoffer Dall
christoffer.dall at linaro.org
Mon Oct 21 10:03:01 EDT 2013
On Fri, Oct 04, 2013 at 01:16:14PM +0100, Marc Zyngier wrote:
> So far, all the VGIC data structures are statically defined by the
> *maximum* number of vcpus and interrupts it supports. It means that
> we always have to oversize it to cater for the worse case.
>
> Start by changing the data structures to be dynamically sizeable,
> and allocate them at runtime.
>
> The sizes are still very static though.
>
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>
> ---
> arch/arm/kvm/arm.c | 5 +-
> include/kvm/arm_vgic.h | 38 ++++++-----
> virt/kvm/arm/vgic.c | 180 +++++++++++++++++++++++++++++++++++++++++++------
> 3 files changed, 184 insertions(+), 39 deletions(-)
>
> diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
> index 9c697db..f0f7a8a 100644
> --- a/arch/arm/kvm/arm.c
> +++ b/arch/arm/kvm/arm.c
> @@ -178,6 +178,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
> kvm->vcpus[i] = NULL;
> }
> }
> +
> + kvm_vgic_destroy(kvm);
> }
>
> int kvm_dev_ioctl_check_extension(long ext)
> @@ -284,6 +286,7 @@ void kvm_arch_vcpu_free(struct kvm_vcpu *vcpu)
> {
> kvm_mmu_free_memory_caches(vcpu);
> kvm_timer_vcpu_terminate(vcpu);
> + kvm_vgic_vcpu_destroy(vcpu);
> kmem_cache_free(kvm_vcpu_cache, vcpu);
> }
>
> @@ -786,7 +789,7 @@ long kvm_arch_vm_ioctl(struct file *filp,
> switch (ioctl) {
> case KVM_CREATE_IRQCHIP: {
> if (vgic_present)
> - return kvm_vgic_create(kvm);
> + return kvm_vgic_create(kvm, VGIC_MAX_CPUS, VGIC_NR_IRQS);
> else
> return -ENXIO;
> }
> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
> index 7e2d158..3cc3a9f 100644
> --- a/include/kvm/arm_vgic.h
> +++ b/include/kvm/arm_vgic.h
> @@ -53,19 +53,18 @@
> * - a bunch of shared interrupts (SPI)
> */
> struct vgic_bitmap {
> - union {
> - u32 reg[VGIC_NR_PRIVATE_IRQS / 32];
> - DECLARE_BITMAP(reg_ul, VGIC_NR_PRIVATE_IRQS);
> - } percpu[VGIC_MAX_CPUS];
> - union {
> - u32 reg[VGIC_NR_SHARED_IRQS / 32];
> - DECLARE_BITMAP(reg_ul, VGIC_NR_SHARED_IRQS);
> - } shared;
> + /*
> + * - One UL per VCPU for private interrupts (assumes UL is at
> + * least 32 bits)
> + * - As many UL as necessary for shared interrupts.
> + */
> + int nr_cpus;
> + unsigned long *bits;
Is this much slower or make for less elegant code if we had a separate
pointer for percpu and shared?
Also, I assume the first UL will be for vcpu 0, etc.
I liked the struct layout we had before
because it was self-documenting.
> };
>
> struct vgic_bytemap {
> - u32 percpu[VGIC_MAX_CPUS][VGIC_NR_PRIVATE_IRQS / 4];
> - u32 shared[VGIC_NR_SHARED_IRQS / 4];
> + int nr_cpus;
> + u32 *regs;
We're duplicating this state around so we can always just pass the
b[yte/it]map pointer to accessor functions right?
Can we document the layout of the *regs in this struct as well?
> };
>
> struct vgic_dist {
> @@ -73,6 +72,9 @@ struct vgic_dist {
> spinlock_t lock;
> bool ready;
>
> + int nr_cpus;
> + int nr_irqs;
> +
> /* Virtual control interface mapping */
> void __iomem *vctrl_base;
>
> @@ -98,12 +100,12 @@ struct vgic_dist {
> /* Level/edge triggered */
> struct vgic_bitmap irq_cfg;
>
> - /* Source CPU per SGI and target CPU */
> - u8 irq_sgi_sources[VGIC_MAX_CPUS][VGIC_NR_SGIS];
> + /* Source CPU per SGI and target CPU : 16 bytes per CPU */
> + u8 *irq_sgi_sources;
>From the accessor below it looks like the ordering is CPU0, SGI0->SGI16,
CPU1, SGI... and so on, so
if I want to know the sources for SGI n for CPU x I get it by
*(irq_sgi_sources + (x * VGIC_NR_SGIS) + n) ?
I sort of like to have the data structure definiton clear without having
to go look at code.
>
> /* Target CPU for each IRQ */
> - u8 irq_spi_cpu[VGIC_NR_SHARED_IRQS];
> - struct vgic_bitmap irq_spi_target[VGIC_MAX_CPUS];
> + u8 *irq_spi_cpu;
> + struct vgic_bitmap *irq_spi_target;
without the array numbers it actually becomes hard to guess what these
do? I assume this is still an array of the structs, just that we are
pointing to n consecutive elements of the structure instead?
Could we add something like the above before the irq_spi_target:
/* Reverse lookup of irq_spu_cpu for faster compute pending */ ?
>
> /* Bitmap indicating which CPU has something pending */
> unsigned long irq_pending_on_cpu;
> @@ -113,11 +115,11 @@ struct vgic_dist {
> struct vgic_cpu {
> #ifdef CONFIG_KVM_ARM_VGIC
> /* per IRQ to LR mapping */
> - u8 vgic_irq_lr_map[VGIC_NR_IRQS];
> + u8 *vgic_irq_lr_map;
>
> /* Pending interrupts on this VCPU */
We could add "Pending interrupt bitmaps on this VCPU" to be crystal
clear.
> DECLARE_BITMAP( pending_percpu, VGIC_NR_PRIVATE_IRQS);
> - DECLARE_BITMAP( pending_shared, VGIC_NR_SHARED_IRQS);
> + unsigned long *pending_shared;
>
> /* Bitmap of used/free list registers */
> DECLARE_BITMAP( lr_used, VGIC_MAX_LRS);
> @@ -147,8 +149,10 @@ struct kvm_exit_mmio;
> int kvm_vgic_set_addr(struct kvm *kvm, unsigned long type, u64 addr);
> int kvm_vgic_hyp_init(void);
> int kvm_vgic_init(struct kvm *kvm);
> -int kvm_vgic_create(struct kvm *kvm);
> +int kvm_vgic_create(struct kvm *kvm, int nr_cpus, int nr_irqs);
> +void kvm_vgic_destroy(struct kvm *kvm);
> int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu);
> +void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu);
> void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu);
> void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu);
> int kvm_vgic_inject_irq(struct kvm *kvm, int cpuid, unsigned int irq_num,
> diff --git a/virt/kvm/arm/vgic.c b/virt/kvm/arm/vgic.c
> index 685fc72..f16c848 100644
> --- a/virt/kvm/arm/vgic.c
> +++ b/virt/kvm/arm/vgic.c
> @@ -96,34 +96,54 @@ static u32 vgic_nr_lr;
>
> static unsigned int vgic_maint_irq;
>
> +static int vgic_init_bitmap(struct vgic_bitmap *b, int nr_cpus, int nr_irqs)
> +{
> + int nr_longs;
> +
> + nr_longs = nr_cpus + BITS_TO_LONGS(nr_irqs - VGIC_NR_PRIVATE_IRQS);
> +
> + b->bits = kzalloc(sizeof(unsigned long) * nr_longs, GFP_KERNEL);
> + if (!b->bits)
> + return -ENOMEM;
> +
> + b->nr_cpus = nr_cpus;
> + return 0;
> +}
> +
> +static void vgic_free_bitmap(struct vgic_bitmap *b)
> +{
> + kfree(b->bits);
> +}
> +
> static u32 *vgic_bitmap_get_reg(struct vgic_bitmap *x,
> int cpuid, u32 offset)
> {
> offset >>= 2;
> if (!offset)
> - return x->percpu[cpuid].reg;
> + return (u32 *)(x->bits + cpuid);
> else
> - return x->shared.reg + offset - 1;
> + return (u32 *)(x->bits + x->nr_cpus) + offset - 1;
this is now completely void of any hints towards what's going on. Could
we add just /* percpu */ and /* SPIs */ at the end of the lines or
something?
> }
>
> static int vgic_bitmap_get_irq_val(struct vgic_bitmap *x,
> int cpuid, int irq)
> {
> if (irq < VGIC_NR_PRIVATE_IRQS)
> - return test_bit(irq, x->percpu[cpuid].reg_ul);
> + return test_bit(irq, x->bits + cpuid);
>
> - return test_bit(irq - VGIC_NR_PRIVATE_IRQS, x->shared.reg_ul);
> + return test_bit(irq - VGIC_NR_PRIVATE_IRQS, x->bits + x->nr_cpus);
> }
>
> static void vgic_bitmap_set_irq_val(struct vgic_bitmap *x, int cpuid,
> int irq, int val)
> {
> - unsigned long *reg;
> + unsigned long *reg = x->bits;
>
> + BUG_ON(!reg);
huh? that would be one terrible bug...
> if (irq < VGIC_NR_PRIVATE_IRQS) {
> - reg = x->percpu[cpuid].reg_ul;
> + reg += cpuid;
> } else {
> - reg = x->shared.reg_ul;
> + reg += x->nr_cpus;
> irq -= VGIC_NR_PRIVATE_IRQS;
> }
>
> @@ -135,24 +155,42 @@ static void vgic_bitmap_set_irq_val(struct vgic_bitmap *x, int cpuid,
>
> static unsigned long *vgic_bitmap_get_cpu_map(struct vgic_bitmap *x, int cpuid)
> {
> - if (unlikely(cpuid >= VGIC_MAX_CPUS))
> - return NULL;
why did we have this before?
> - return x->percpu[cpuid].reg_ul;
> + return x->bits + cpuid;
> }
>
> static unsigned long *vgic_bitmap_get_shared_map(struct vgic_bitmap *x)
> {
> - return x->shared.reg_ul;
> + return x->bits + x->nr_cpus;
> +}
> +
> +static int vgic_init_bytemap(struct vgic_bytemap *x, int nr_cpus, int nr_irqs)
> +{
> + int size;
> +
> + size = nr_cpus * VGIC_NR_PRIVATE_IRQS;
> + size += nr_irqs - VGIC_NR_PRIVATE_IRQS;
> +
> + x->regs = kzalloc(size, GFP_KERNEL);
> + if (!x->regs)
> + return -ENOMEM;
> +
> + x->nr_cpus = nr_cpus;
> + return 0;
> +}
> +
> +static void vgic_free_bytemap(struct vgic_bytemap *b)
> +{
> + kfree(b->regs);
> }
>
> static u32 *vgic_bytemap_get_reg(struct vgic_bytemap *x, int cpuid, u32 offset)
> {
> - offset >>= 2;
> - BUG_ON(offset > (VGIC_NR_IRQS / 4));
> - if (offset < 8)
> - return x->percpu[cpuid] + offset;
> + if (offset < 32)
> + offset += cpuid * VGIC_NR_PRIVATE_IRQS;
> else
> - return x->shared + offset - 8;
> + offset += (x->nr_cpus - 1) * VGIC_NR_PRIVATE_IRQS;
> +
> + return x->regs + (offset / sizeof(u32));
> }
>
> #define VGIC_CFG_LEVEL 0
> @@ -733,6 +771,11 @@ bool vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
> return true;
> }
>
> +static u8 *vgic_get_sgi_sources(struct vgic_dist *dist, int vcpu_id, int sgi)
> +{
> + return dist->irq_sgi_sources + vcpu_id * VGIC_NR_SGIS + sgi;
> +}
> +
> static void vgic_dispatch_sgi(struct kvm_vcpu *vcpu, u32 reg)
> {
> struct kvm *kvm = vcpu->kvm;
> @@ -765,7 +808,7 @@ static void vgic_dispatch_sgi(struct kvm_vcpu *vcpu, u32 reg)
> if (target_cpus & 1) {
> /* Flag the SGI as pending */
> vgic_dist_irq_set(vcpu, sgi);
> - dist->irq_sgi_sources[c][sgi] |= 1 << vcpu_id;
> + *vgic_get_sgi_sources(dist, c, sgi) |= 1 << vcpu_id;
> kvm_debug("SGI%d from CPU%d to CPU%d\n", sgi, vcpu_id, c);
> }
>
> @@ -908,14 +951,14 @@ static bool vgic_queue_sgi(struct kvm_vcpu *vcpu, int irq)
> int vcpu_id = vcpu->vcpu_id;
> int c;
>
> - sources = dist->irq_sgi_sources[vcpu_id][irq];
> + sources = *vgic_get_sgi_sources(dist, vcpu_id, irq);
>
> for_each_set_bit(c, &sources, VGIC_MAX_CPUS) {
> if (vgic_queue_irq(vcpu, c, irq))
> clear_bit(c, &sources);
> }
>
> - dist->irq_sgi_sources[vcpu_id][irq] = sources;
> + *vgic_get_sgi_sources(dist, vcpu_id, irq) = sources;
>
> /*
> * If the sources bitmap has been cleared it means that we
> @@ -1243,15 +1286,44 @@ static irqreturn_t vgic_maintenance_handler(int irq, void *data)
> return IRQ_HANDLED;
> }
>
> +static void vgic_vcpu_free_maps(struct vgic_cpu *vgic_cpu)
> +{
> + kfree(vgic_cpu->pending_shared);
> + kfree(vgic_cpu->vgic_irq_lr_map);
> +}
> +
> +static int vgic_vcpu_init_maps(struct vgic_cpu *vgic_cpu, int nr_irqs)
> +{
> + vgic_cpu->pending_shared = kzalloc(nr_irqs - VGIC_NR_PRIVATE_IRQS,
> + GFP_KERNEL);
aren't you allocate x8 too many bits here?
> + vgic_cpu->vgic_irq_lr_map = kzalloc(nr_irqs, GFP_KERNEL);
> +
> + if (!vgic_cpu->pending_shared || !vgic_cpu->vgic_irq_lr_map) {
> + vgic_vcpu_free_maps(vgic_cpu);
> + return -ENOMEM;
> + }
> +
> + return 0;
> +}
> +
> +void kvm_vgic_vcpu_destroy(struct kvm_vcpu *vcpu)
> +{
> + vgic_vcpu_free_maps(&vcpu->arch.vgic_cpu);
> +}
> +
> int kvm_vgic_vcpu_init(struct kvm_vcpu *vcpu)
> {
> struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
> struct vgic_dist *dist = &vcpu->kvm->arch.vgic;
> - int i;
> + int i, ret;
>
> if (!irqchip_in_kernel(vcpu->kvm))
> return 0;
>
> + ret = vgic_vcpu_init_maps(vgic_cpu, dist->nr_irqs);
> + if (ret)
> + return ret;
> +
> if (vcpu->vcpu_id >= VGIC_MAX_CPUS)
> return -EBUSY;
>
> @@ -1383,6 +1455,68 @@ out:
> return ret;
> }
>
> +static void vgic_free_maps(struct vgic_dist *dist)
> +{
> + int i;
> +
> + vgic_free_bitmap(&dist->irq_enabled);
> + vgic_free_bitmap(&dist->irq_state);
> + vgic_free_bitmap(&dist->irq_active);
> + vgic_free_bitmap(&dist->irq_cfg);
> + vgic_free_bytemap(&dist->irq_priority);
> + if (dist->irq_spi_target)
> + for (i = 0; i < dist->nr_cpus; i++)
> + vgic_free_bitmap(&dist->irq_spi_target[i]);
> + kfree(dist->irq_sgi_sources);
> + kfree(dist->irq_spi_cpu);
> + kfree(dist->irq_spi_target);
I would love for this to be ordered like the fields in the structure,
but this is obviously not a functional requirement.
> +}
> +
> +static int vgic_init_maps(struct vgic_dist *dist, int nr_cpus, int nr_irqs)
> +{
> + int ret = 0, i;
no need to do ret = 0 here.
> +
> + dist->nr_cpus = nr_cpus;
> + dist->nr_irqs = nr_irqs;
> +
> + ret = vgic_init_bitmap(&dist->irq_enabled, nr_cpus, nr_irqs);
> + ret |= vgic_init_bitmap(&dist->irq_state, nr_cpus, nr_irqs);
> + ret |= vgic_init_bitmap(&dist->irq_active, nr_cpus, nr_irqs);
> + ret |= vgic_init_bitmap(&dist->irq_cfg, nr_cpus, nr_irqs);
> + ret |= vgic_init_bytemap(&dist->irq_priority, nr_cpus, nr_irqs);
> +
> + if (!ret) {
> + dist->irq_sgi_sources = kzalloc(nr_cpus * VGIC_NR_SGIS,
> + GFP_KERNEL);
> + dist->irq_spi_cpu = kzalloc(nr_irqs - VGIC_NR_PRIVATE_IRQS,
> + GFP_KERNEL);
We could redefine VGIC_NR_SHARED_IRQS() to take nr_irqs as an
argument...
> + dist->irq_spi_target = kzalloc(sizeof(*dist->irq_spi_target) * nr_cpus,
> + GFP_KERNEL);
> + if (!dist->irq_sgi_sources ||
> + !dist->irq_spi_cpu ||
> + !dist->irq_spi_target) {
> + ret = -ENOMEM;
> + goto out;
> + }
> +
> + for (i = 0; i < nr_cpus; i++)
> + ret |= vgic_init_bitmap(&dist->irq_spi_target[i],
> + nr_cpus, nr_irqs);
> +
> + }
> +
> +out:
> + if (ret)
> + vgic_free_maps(dist);
> +
> + return ret;
> +}
> +
> +void kvm_vgic_destroy(struct kvm *kvm)
> +{
> + vgic_free_maps(&kvm->arch.vgic);
> +}
> +
> int kvm_vgic_init(struct kvm *kvm)
> {
> int ret = 0, i;
> @@ -1416,7 +1550,7 @@ out:
> return ret;
> }
>
> -int kvm_vgic_create(struct kvm *kvm)
> +int kvm_vgic_create(struct kvm *kvm, int nr_cpus, int nr_irqs)
> {
> int ret = 0;
>
> @@ -1432,6 +1566,10 @@ int kvm_vgic_create(struct kvm *kvm)
> kvm->arch.vgic.vgic_dist_base = VGIC_ADDR_UNDEF;
> kvm->arch.vgic.vgic_cpu_base = VGIC_ADDR_UNDEF;
>
> + ret = vgic_init_maps(&kvm->arch.vgic, nr_cpus, nr_irqs);
> + if (ret)
> + kvm_err("Unable to allocate maps\n");
> +
> out:
> mutex_unlock(&kvm->lock);
> return ret;
> --
> 1.8.2.3
>
>
-Christoffer
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