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Re: [Xen-devel] [PATCH v2 14/15] xen/arm: vgic: Drop iactive, ipend, pendsgi field



On Thu, 2015-01-29 at 18:25 +0000, Julien Grall wrote:
> The current VGIC code doesn't support to change the pending and active status
> of an IRQ via the (re-)distributor.
> If we plan to support it in the future, it will unlikely require a specific
> bitfield as we already store the status per vIRQ.

I think we would want to track the state like we do for enabled, since
walking 32 virqs to construct the value would be a bit expensive.

Stefano, what do you think?

> Rather than wasting memory for nothing, drop thoses field. Any read to

"those"

> these registers will be RAZ and any write will print an error and inject
> a data abort to the guest.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxxxxx>
> 
> ---
>     Changes in v2:
>         - Patch added
> ---
>  xen/arch/arm/vgic-v2.c     |  71 +++++--------------------
>  xen/arch/arm/vgic-v3.c     | 125 
> +++++++++++++++------------------------------
>  xen/include/asm-arm/vgic.h |   2 +-
>  3 files changed, 55 insertions(+), 143 deletions(-)
> 
> diff --git a/xen/arch/arm/vgic-v2.c b/xen/arch/arm/vgic-v2.c
> index 1a02541..3cf67a9 100644
> --- a/xen/arch/arm/vgic-v2.c
> +++ b/xen/arch/arm/vgic-v2.c
> @@ -94,41 +94,15 @@ static int vgic_v2_distr_mmio_read(struct vcpu *v, 
> mmio_info_t *info)
>          vgic_unlock_rank(v, rank, flags);
>          return 1;
>  
> +    /* Read the pending status of an IRQ via GICD is not supported */
>      case GICD_ISPENDR ... GICD_ISPENDRN:
> -        if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, gicd_reg - GICD_ISPENDR, DABT_WORD);
> -        if ( rank == NULL) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = vgic_byte_read(rank->ipend, dabt.sign, gicd_reg);
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> -
>      case GICD_ICPENDR ... GICD_ICPENDRN:
> -        if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 0, gicd_reg - GICD_ICPENDR, DABT_WORD);
> -        if ( rank == NULL) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = vgic_byte_read(rank->ipend, dabt.sign, gicd_reg);
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        goto read_as_zero;
>  
> +    /* Read the active status of an IRQ via GICD is not supported */
>      case GICD_ISACTIVER ... GICD_ISACTIVERN:
> -        if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, gicd_reg - GICD_ISACTIVER, DABT_WORD);
> -        if ( rank == NULL) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = rank->iactive;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> -
>      case GICD_ICACTIVER ... GICD_ICACTIVERN:
> -        if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, gicd_reg - GICD_ICACTIVER, DABT_WORD);
> -        if ( rank == NULL) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = rank->iactive;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        goto read_as_zero;
>  
>      case GICD_ITARGETSR ... GICD_ITARGETSRN:
>          if ( dabt.size != DABT_BYTE && dabt.size != DABT_WORD ) goto 
> bad_width;
> @@ -174,23 +148,10 @@ static int vgic_v2_distr_mmio_read(struct vcpu *v, 
> mmio_info_t *info)
>          *r = 0xdeadbeef;
>          return 1;
>  
> +    /* Setting/Clearing the SGI pending bit via GICD is not supported */
>      case GICD_CPENDSGIR ... GICD_CPENDSGIRN:
> -        if ( dabt.size != DABT_BYTE && dabt.size != DABT_WORD ) goto 
> bad_width;
> -        rank = vgic_rank_offset(v, 1, gicd_reg - GICD_CPENDSGIR, DABT_WORD);
> -        if ( rank == NULL) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = vgic_byte_read(rank->pendsgi, dabt.sign, gicd_reg);
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> -
>      case GICD_SPENDSGIR ... GICD_SPENDSGIRN:
> -        if ( dabt.size != DABT_BYTE && dabt.size != DABT_WORD ) goto 
> bad_width;
> -        rank = vgic_rank_offset(v, 1, gicd_reg - GICD_SPENDSGIR, DABT_WORD);
> -        if ( rank == NULL) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = vgic_byte_read(rank->pendsgi, dabt.sign, gicd_reg);
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        goto read_as_zero;
>  
>      /* Implementation defined -- read as zero */
>      case 0xfd0 ... 0xfe4:
> @@ -346,21 +307,17 @@ static int vgic_v2_distr_mmio_write(struct vcpu *v, 
> mmio_info_t *info)
>  
>      case GICD_ISACTIVER ... GICD_ISACTIVERN:
>          if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, gicd_reg - GICD_ISACTIVER, DABT_WORD);
> -        if ( rank == NULL) goto write_ignore;
> -        vgic_lock_rank(v, rank, flags);
> -        rank->iactive &= ~*r;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        printk(XENLOG_G_ERR
> +               "%pv: vGICD: unhandled word write %#"PRIregister" to 
> ISACTIVER%d\n",
> +               v, *r, gicd_reg - GICD_ISACTIVER);
> +        return 0;
>  
>      case GICD_ICACTIVER ... GICD_ICACTIVERN:
>          if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, gicd_reg - GICD_ICACTIVER, DABT_WORD);
> -        if ( rank == NULL) goto write_ignore;
> -        vgic_lock_rank(v, rank, flags);
> -        rank->iactive &= ~*r;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        printk(XENLOG_ERR
> +               "%pv: vGICD: unhandled word write %#"PRIregister" to 
> ICACTIVER%d\n",
> +               v, *r, gicd_reg - GICD_ICACTIVER);
> +        return 0;
>  
>      case GICD_ITARGETSR ... GICD_ITARGETSR + 7:
>          /* SGI/PPI target is read only */
> diff --git a/xen/arch/arm/vgic-v3.c b/xen/arch/arm/vgic-v3.c
> index b59cc49..c68ef05 100644
> --- a/xen/arch/arm/vgic-v3.c
> +++ b/xen/arch/arm/vgic-v3.c
> @@ -306,38 +306,16 @@ static int __vgic_v3_distr_common_mmio_read(const char 
> *name, struct vcpu *v,
>          *r = rank->ienable;
>          vgic_unlock_rank(v, rank, flags);
>          return 1;
> +    /* Read the pending status of an IRQ via GICD/GICR is not supported */
>      case GICD_ISPENDR ... GICD_ISPENDRN:
> -        if ( dabt.size != DABT_BYTE && dabt.size != DABT_WORD ) goto 
> bad_width;
> -        rank = vgic_rank_offset(v, 1, reg - GICD_ISPENDR, DABT_WORD);
> -        if ( rank == NULL ) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = vgic_byte_read(rank->ipend, dabt.sign, reg);
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
>      case GICD_ICPENDR ... GICD_ICPENDRN:
> -        if ( dabt.size != DABT_BYTE && dabt.size != DABT_WORD ) goto 
> bad_width;
> -        rank = vgic_rank_offset(v, 1, reg - GICD_ICPENDR, DABT_WORD);
> -        if ( rank == NULL ) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = vgic_byte_read(rank->ipend, dabt.sign, reg);
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        goto read_as_zero;
> +
> +    /* Read the active status of an IRQ via GICD/GICR is not supported */
>      case GICD_ISACTIVER ... GICD_ISACTIVERN:
> -        if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, reg - GICD_ISACTIVER, DABT_WORD);
> -        if ( rank == NULL ) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = rank->iactive;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
>      case GICD_ICACTIVER ... GICD_ICACTIVERN:
> -        if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, reg - GICD_ICACTIVER, DABT_WORD);
> -        if ( rank == NULL ) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = rank->iactive;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        goto read_as_zero;
> +
>      case GICD_IPRIORITYR ... GICD_IPRIORITYRN:
>          if ( dabt.size != DABT_BYTE && dabt.size != DABT_WORD ) goto 
> bad_width;
>          rank = vgic_rank_offset(v, 8, reg - GICD_IPRIORITYR, DABT_WORD);
> @@ -415,36 +393,32 @@ static int __vgic_v3_distr_common_mmio_write(const char 
> *name, struct vcpu *v,
>          return 1;
>      case GICD_ISPENDR ... GICD_ISPENDRN:
>          if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, reg - GICD_ISPENDR, DABT_WORD);
> -        if ( rank == NULL ) goto write_ignore;
> -        vgic_lock_rank(v, rank, flags);
> -        rank->ipend = *r;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        printk(XENLOG_G_ERR
> +               "%pv: %s: unhandled word write %#"PRIregister" to 
> ISPENDR%d\n",
> +               v, name, *r, reg - GICD_ISPENDR);
> +        return 0;
> +
>      case GICD_ICPENDR ... GICD_ICPENDRN:
>          if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, reg - GICD_ICPENDR, DABT_WORD);
> -        if ( rank == NULL ) goto write_ignore;
> -        vgic_lock_rank(v, rank, flags);
> -        rank->ipend &= ~*r;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        printk(XENLOG_G_ERR
> +               "%pv: %s: unhandled word write %#"PRIregister" to 
> ICPENDR%d\n",
> +               v, name, *r, reg - GICD_ICPENDR);
> +        return 0;
> +
>      case GICD_ISACTIVER ... GICD_ISACTIVERN:
>          if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, reg - GICD_ISACTIVER, DABT_WORD);
> -        if ( rank == NULL ) goto write_ignore;
> -        vgic_lock_rank(v, rank, flags);
> -        rank->iactive &= ~*r;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        printk(XENLOG_G_ERR
> +               "%pv: %s: unhandled word write %#"PRIregister" to 
> ISACTIVER%d\n",
> +               v, name, *r, reg - GICD_ISACTIVER);
> +        return 0;
> +
>      case GICD_ICACTIVER ... GICD_ICACTIVERN:
>          if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, reg - GICD_ICACTIVER, DABT_WORD);
> -        if ( rank == NULL ) goto write_ignore;
> -        vgic_lock_rank(v, rank, flags);
> -        rank->iactive &= ~*r;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        printk(XENLOG_G_ERR
> +               "%pv: %s: unhandled word write %#"PRIregister" to 
> ICACTIVER%d\n",
> +               v, name, *r, reg - GICD_ICACTIVER);
> +        return 0;
> +
>      case GICD_IPRIORITYR ... GICD_IPRIORITYRN:
>          if ( dabt.size != DABT_BYTE && dabt.size != DABT_WORD ) goto 
> bad_width;
>          rank = vgic_rank_offset(v, 8, reg - GICD_IPRIORITYR, DABT_WORD);
> @@ -496,8 +470,6 @@ static int vgic_v3_rdistr_sgi_mmio_read(struct vcpu *v, 
> mmio_info_t *info,
>      struct hsr_dabt dabt = info->dabt;
>      struct cpu_user_regs *regs = guest_cpu_user_regs();
>      register_t *r = select_user_reg(regs, dabt.reg);
> -    struct vgic_irq_rank *rank;
> -    unsigned long flags;
>  
>      switch ( gicr_reg )
>      {
> @@ -517,22 +489,12 @@ static int vgic_v3_rdistr_sgi_mmio_read(struct vcpu *v, 
> mmio_info_t *info,
>            */
>          return __vgic_v3_distr_common_mmio_read("vGICR: SGI", v, info,
>                                                  gicr_reg);
> +
> +    /* Read the pending status of an SGI is via GICR is not supported */
>      case GICR_ISPENDR0:
> -        if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, gicr_reg - GICR_ISPENDR0, DABT_WORD);
> -        if ( rank == NULL ) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = rank->pendsgi;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
>      case GICR_ICPENDR0:
> -        if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, gicr_reg - GICR_ICPENDR0, DABT_WORD);
> -        if ( rank == NULL ) goto read_as_zero;
> -        vgic_lock_rank(v, rank, flags);
> -        *r = rank->pendsgi;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        goto read_as_zero;
> +
>      case GICR_NSACR:
>          /* We do not implement security extensions for guests, read zero */
>          goto read_as_zero_32;
> @@ -562,8 +524,6 @@ static int vgic_v3_rdistr_sgi_mmio_write(struct vcpu *v, 
> mmio_info_t *info,
>      struct hsr_dabt dabt = info->dabt;
>      struct cpu_user_regs *regs = guest_cpu_user_regs();
>      register_t *r = select_user_reg(regs, dabt.reg);
> -    struct vgic_irq_rank *rank;
> -    unsigned long flags;
>  
>      switch ( gicr_reg )
>      {
> @@ -585,22 +545,18 @@ static int vgic_v3_rdistr_sgi_mmio_write(struct vcpu 
> *v, mmio_info_t *info,
>                                                   info, gicr_reg);
>      case GICR_ISPENDR0:
>          if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, gicr_reg - GICR_ISACTIVER0, DABT_WORD);
> -        if ( rank == NULL ) goto write_ignore;
> -        vgic_lock_rank(v, rank, flags);
> -        /* TODO: we just store the SGI pending status. Handle it properly */
> -        rank->pendsgi |= *r;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        printk(XENLOG_G_ERR
> +               "%pv: vGICR: SGI: unhandled word write %#"PRIregister" to 
> ISPENDR0\n",
> +               v, *r);
> +        return 0;
> +
>      case GICR_ICPENDR0:
>          if ( dabt.size != DABT_WORD ) goto bad_width;
> -        rank = vgic_rank_offset(v, 1, gicr_reg - GICR_ISACTIVER0, DABT_WORD);
> -        if ( rank == NULL ) goto write_ignore;
> -        vgic_lock_rank(v, rank, flags);
> -        /* TODO: we just store the SGI pending status. Handle it properly */
> -        rank->pendsgi &= ~*r;
> -        vgic_unlock_rank(v, rank, flags);
> -        return 1;
> +        printk(XENLOG_G_ERR
> +               "%pv: vGICR: SGI: unhandled word write %#"PRIregister" to 
> ICPENDR0\n",
> +               v, *r);
> +        return 0;
> +
>      case GICR_NSACR:
>          /* We do not implement security extensions for guests, write ignore 
> */
>          goto write_ignore_32;
> @@ -620,7 +576,6 @@ bad_width:
>  
>  write_ignore_32:
>      if ( dabt.size != DABT_WORD ) goto bad_width;
> -write_ignore:
>      return 1;
>  }
>  
> diff --git a/xen/include/asm-arm/vgic.h b/xen/include/asm-arm/vgic.h
> index 74d5a4e..0c7da7f 100644
> --- a/xen/include/asm-arm/vgic.h
> +++ b/xen/include/asm-arm/vgic.h
> @@ -85,7 +85,7 @@ struct pending_irq
>  /* Represents state corresponding to a block of 32 interrupts */
>  struct vgic_irq_rank {
>      spinlock_t lock; /* Covers access to all other members of this struct */
> -    uint32_t ienable, iactive, ipend, pendsgi;
> +    uint32_t ienable;
>      uint32_t icfg[2];
>      uint32_t ipriority[8];
>      union {



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