On 29/01/2015 22:48, Radim Krčmář wrote:
> We want to support mixed modes and the easiest solution is to avoid
> optimizing those weird and unlikely scenarios.
>
> Signed-off-by: Radim Krčmář <rkrcmar@xxxxxxxxxx>
> ---
> arch/x86/include/asm/kvm_host.h | 1 +
> arch/x86/kvm/lapic.c | 16 ++++++++++++++++
> arch/x86/kvm/lapic.h | 4 ++++
> 3 files changed, 21 insertions(+)
>
> diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> index 26d0f0f646d3..fec3188cabbb 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -554,6 +554,7 @@ struct kvm_arch_memory_slot {
>
> struct kvm_apic_map {
> struct rcu_head rcu;
> + u8 mode;
> u8 ldr_bits;
> /* fields bellow are used to decode ldr values in different modes */
> u32 cid_shift, cid_mask, lid_mask;
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index fab007509047..621d9df6ac63 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -162,16 +162,19 @@ static void recalculate_apic_map(struct kvm *kvm)
> new->ldr_bits = 32;
> new->cid_shift = 16;
> new->cid_mask = new->lid_mask = 0xffff;
> + new->mode |= KVM_APIC_MODE_X2APIC;
> } else if (kvm_apic_get_reg(apic, APIC_LDR)) {
> if (kvm_apic_get_reg(apic, APIC_DFR) ==
> APIC_DFR_CLUSTER) {
> new->cid_shift = 4;
> new->cid_mask = 0xf;
> new->lid_mask = 0xf;
> + new->mode |= KVM_APIC_MODE_XAPIC_CLUSTER;
> } else {
> new->cid_shift = 8;
> new->cid_mask = 0;
> new->lid_mask = 0xff;
> + new->mode |= KVM_APIC_MODE_XAPIC_FLAT;
> }
> }
>
> @@ -201,6 +204,13 @@ static void recalculate_apic_map(struct kvm *kvm)
>
> if (aid < ARRAY_SIZE(new->phys_map))
> new->phys_map[aid] = apic;
> +
> + /* The logical map is definitely wrong if we have multiple
> + * modes at the same time. Physical is still right though.
> + */
> + if (hweight8(new->mode) != 1)
Better (more optimized):
if (new->mode & (new->mode - 1))
Please add a comment to kvm_irq_delivery_to_apic_fast to explain what
you are doing.
> + continue;
> +
> if (lid && cid < ARRAY_SIZE(new->logical_map))
> new->logical_map[cid][ffs(lid) - 1] = apic;
> }
> @@ -720,6 +730,12 @@ bool kvm_irq_delivery_to_apic_fast(struct kvm *kvm, struct kvm_lapic *src,
> if (cid >= ARRAY_SIZE(map->logical_map))
> goto out;
>
> + if (hweight8(map->mode) != 1) {
> + /* Not deliverable with optimized map. */
> + ret = false;
> + goto out;
> + }
Put this before the computation of cid and mda. The cid and mda are all
wrong with a mixed map, and the result of the "if" before is influenced
by the wrong cid. Fixed by patch 8, but better get it right here.
Paolo
> dst = map->logical_map[cid];
>
> bitmap = apic_logical_id(map, mda);
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index c1ef25c89508..fd0197a93862 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -8,6 +8,10 @@
> #define KVM_APIC_INIT 0
> #define KVM_APIC_SIPI 1
>
> +#define KVM_APIC_MODE_XAPIC_FLAT (1 << 0)
> +#define KVM_APIC_MODE_XAPIC_CLUSTER (1 << 1)
> +#define KVM_APIC_MODE_X2APIC (1 << 2)
> +
> struct kvm_timer {
> struct hrtimer timer;
> s64 period; /* unit: ns */
>
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