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

[Julien Grall <julien.grall@linaro.org>]

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.

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

---
    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 {
-- 
2.1.4