Re: [Qemu-devel] [PATCH V3 2/2] arm_gicv3_kvm: kvm_dist_get/put: skip the registers banked by GICR

[Auger Eric <eric.auger@redhat.com>]

Hi Shannon,

On 05/23/2018 05:53 AM, Shannon Zhao wrote:
> While we skip the GIC_INTERNAL irqs, we don't change the register offset
> accordingly. This will overlap the GICR registers value and leave the
> last GIC_INTERNAL irq's registers out of update.
> 
> Fix this by skipping the registers banked by GICR.
> 
> Also for migration compatibility if the migration source (old version
> qemu) doesn't send gicd_no_shift_bug = 1 to destination, then we shift
> the data of PPI to get the right data for SPI.
> 
> Fixes: 367b9f527becdd20ddf116e17a3c0c2bbc486920
> Cc: qemu-stable@nongnu.org
> Signed-off-by: Shannon Zhao <zhaoshenglong@huawei.com>
> ---
> Changes in V3: add migration compatibility and fix code style
> ---
>  hw/intc/arm_gicv3_common.c         | 36 ++++++++++++++++++++++++
>  hw/intc/arm_gicv3_kvm.c            | 56 +++++++++++++++++++++++++++++++++++++-
>  include/hw/intc/arm_gicv3_common.h |  1 +
>  3 files changed, 92 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/intc/arm_gicv3_common.c b/hw/intc/arm_gicv3_common.c
> index 7b54d52..f93e5d2 100644
> --- a/hw/intc/arm_gicv3_common.c
> +++ b/hw/intc/arm_gicv3_common.c
> @@ -141,6 +141,38 @@ static const VMStateDescription vmstate_gicv3_cpu = {
>      }
>  };
>  
> +static int gicv3_gicd_no_shift_bug_pre_load(void *opaque)
> +{
> +    GICv3State *cs = opaque;
> +
> +   /*
> +    * If the gicd_no_shift_bug subsection is not transferred this
> +    * means gicd_no_shift_bug is 0x0 (which might not be the same as
> +    * our reset value).
> +    */
> +    cs->gicd_no_shift_bug = 0x0;
> +    return 0;
> +}
> +
> +static bool gicv3_gicd_no_shift_bug_needed(void *opaque)
> +{
> +    GICv3State *cs = opaque;
> +
> +    return cs->gicd_no_shift_bug;
> +}
> +
> +const VMStateDescription vmstate_gicv3_gicd_no_shift_bug = {
> +    .name = "arm_gicv3/gicd_no_shift_bug",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .pre_load = gicv3_gicd_no_shift_bug_pre_load,
> +    .needed = gicv3_gicd_no_shift_bug_needed,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_BOOL(gicd_no_shift_bug, GICv3State),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
>  static const VMStateDescription vmstate_gicv3 = {
>      .name = "arm_gicv3",
>      .version_id = 1,
> @@ -165,6 +197,10 @@ static const VMStateDescription vmstate_gicv3 = {
>          VMSTATE_STRUCT_VARRAY_POINTER_UINT32(cpu, GICv3State, num_cpu,
>                                               vmstate_gicv3_cpu, GICv3CPUState),
>          VMSTATE_END_OF_LIST()
> +    },
> +    .subsections = (const VMStateDescription * []) {
> +        &vmstate_gicv3_gicd_no_shift_bug,
> +        NULL
>      }
>  };
>  
> diff --git a/hw/intc/arm_gicv3_kvm.c b/hw/intc/arm_gicv3_kvm.c
> index 3536795..bd961f1 100644
> --- a/hw/intc/arm_gicv3_kvm.c
> +++ b/hw/intc/arm_gicv3_kvm.c
> @@ -136,6 +136,12 @@ static void kvm_dist_get_priority(GICv3State *s, uint32_t offset, uint8_t *bmp)
>      int irq;
>  
>      field = (uint32_t *)bmp;
> +    /* For the KVM GICv3, affinity routing is always enabled, and the first 8
> +     * GICD_IPRIORITYR<n> registers are always RAZ/WI. The corresponding
> +     * functionality is replaced by GICR_IPRIORITYR<n>. So it doesn't need to
> +     * sync them.
> +     */
> +    offset += (8 * sizeof(uint32_t));
Now I am unclear about the semantics of the s->gicd_ipriority & friends.
With that change, is it supposed to contain only the states of SPIs or
contain the RAZ states of PPI/SGIs + states of SPIs. The array is
dimensionned to contain states for PPI/SGI+SPIs, right? In other words,
shouldn't we also shift field?

Thanks

Eric
>      for_each_dist_irq_reg(irq, s->num_irq, 8) {
>          kvm_gicd_access(s, offset, &reg, false);
>          *field = reg;
> @@ -149,7 +155,18 @@ static void kvm_dist_put_priority(GICv3State *s, uint32_t offset, uint8_t *bmp)
>      uint32_t reg, *field;
>      int irq;
>  
> -    field = (uint32_t *)bmp;
> +    if (!s->gicd_no_shift_bug) {
> +        field = (uint32_t *)(bmp + 8 * sizeof(uint32_t));
> +    } else {
> +        field = (uint32_t *)bmp;
> +    }
> +
> +    /* For the KVM GICv3, affinity routing is always enabled, and the first 8
> +     * GICD_IPRIORITYR<n> registers are always RAZ/WI. The corresponding
> +     * functionality is replaced by GICR_IPRIORITYR<n>. So it doesn't need to
> +     * sync them.
> +     */
> +    offset += (8 * sizeof(uint32_t));
in the old to new migration scenario, IIUC,
bmp contains state of 32 internal PPI/SGI(RAZ) + s->num_irq-32 SPIs
Here aren't you "putting" the RAZ state of the 32 PPI/SGIs into the
first 32 SPIs here?

Thanks

Eric
>      for_each_dist_irq_reg(irq, s->num_irq, 8) {
>          reg = *field;
>          kvm_gicd_access(s, offset, &reg, true);
> @@ -164,6 +181,12 @@ static void kvm_dist_get_edge_trigger(GICv3State *s, uint32_t offset,
>      uint32_t reg;
>      int irq;
>  
> +    /* For the KVM GICv3, affinity routing is always enabled, and the first 2
> +     * GICD_ICFGR<n> registers are always RAZ/WI. The corresponding
> +     * functionality is replaced by GICR_ICFGR<n>. So it doesn't need to sync
> +     * them.
> +     */
> +    offset += (2 * sizeof(uint32_t));
>      for_each_dist_irq_reg(irq, s->num_irq, 2) {
>          kvm_gicd_access(s, offset, &reg, false);
>          reg = half_unshuffle32(reg >> 1);
> @@ -181,6 +204,16 @@ static void kvm_dist_put_edge_trigger(GICv3State *s, uint32_t offset,
>      uint32_t reg;
>      int irq;
>  
> +    if (!s->gicd_no_shift_bug) {
> +        bmp += (2 * sizeof(uint32_t));
> +    }
> +
> +    /* For the KVM GICv3, affinity routing is always enabled, and the first 2
> +     * GICD_ICFGR<n> registers are always RAZ/WI. The corresponding
> +     * functionality is replaced by GICR_ICFGR<n>. So it doesn't need to sync
> +     * them.
> +     */
> +    offset += (2 * sizeof(uint32_t));
>      for_each_dist_irq_reg(irq, s->num_irq, 2) {
>          reg = *gic_bmp_ptr32(bmp, irq);
>          if (irq % 32 != 0) {
> @@ -222,6 +255,12 @@ static void kvm_dist_getbmp(GICv3State *s, uint32_t offset, uint32_t *bmp)
>      uint32_t reg;
>      int irq;
>  
> +    /* For the KVM GICv3, affinity routing is always enabled, and the
> +     * GICD_IGROUPR0/GICD_ISENABLER0/GICD_ISPENDR0/GICD_ISACTIVER0 registers
> +     * are always RAZ/WI. The corresponding functionality is replaced by the
> +     * GICR registers. So it doesn't need to sync them.
> +     */
> +    offset += (1 * sizeof(uint32_t));
>      for_each_dist_irq_reg(irq, s->num_irq, 1) {
>          kvm_gicd_access(s, offset, &reg, false);
>          *gic_bmp_ptr32(bmp, irq) = reg;
> @@ -235,6 +274,20 @@ static void kvm_dist_putbmp(GICv3State *s, uint32_t offset,
>      uint32_t reg;
>      int irq;
>  
> +    if (!s->gicd_no_shift_bug) {
> +        bmp += (1 * sizeof(uint32_t));
> +    }
> +
> +    /* For the KVM GICv3, affinity routing is always enabled, and the
> +     * GICD_IGROUPR0/GICD_ISENABLER0/GICD_ISPENDR0/GICD_ISACTIVER0 registers
> +     * are always RAZ/WI. The corresponding functionality is replaced by the
> +     * GICR registers. So it doesn't need to sync them.
> +     */
> +    offset += (1 * sizeof(uint32_t));
> +    if (clroffset != 0) {
> +        clroffset += (1 * sizeof(uint32_t));
> +    }
> +
>      for_each_dist_irq_reg(irq, s->num_irq, 1) {
>          /* If this bitmap is a set/clear register pair, first write to the
>           * clear-reg to clear all bits before using the set-reg to write
> @@ -651,6 +704,7 @@ static void kvm_arm_gicv3_reset(DeviceState *dev)
>          return;
>      }
>  
> +    s->gicd_no_shift_bug = 1;
>      kvm_arm_gicv3_put(s);
>  }
>  
> diff --git a/include/hw/intc/arm_gicv3_common.h b/include/hw/intc/arm_gicv3_common.h
> index bccdfe1..13c28c0 100644
> --- a/include/hw/intc/arm_gicv3_common.h
> +++ b/include/hw/intc/arm_gicv3_common.h
> @@ -217,6 +217,7 @@ struct GICv3State {
>      uint32_t revision;
>      bool security_extn;
>      bool irq_reset_nonsecure;
> +    bool gicd_no_shift_bug;
>  
>      int dev_fd; /* kvm device fd if backed by kvm vgic support */
>      Error *migration_blocker;
>