Re: [PATCH for-11.2 1/4] hw/intc/arm_gicv5: Use cached IRS_IST_BASER.VALID state

[Jim MacArthur <jim.macarthur@linaro.org>]

On Tue, Nov 03, 2026 at 05:26:13PM +0000, Peter Maydell wrote:
> When the guest writes to IRS_IST_BASER we effectively cache the value
> of the VALID bit in the GICv5ISTConfig valid field entry.  In a few
> places we check whether the IST is valid by doing a bit extract on
> the register value; switch those to look at cfg->structure instead.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  hw/intc/arm_gicv5.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
> 
> diff --git a/hw/intc/arm_gicv5.c b/hw/intc/arm_gicv5.c
> index 5d0a50ab6aa..d0a8574916b 100644
> --- a/hw/intc/arm_gicv5.c
> +++ b/hw/intc/arm_gicv5.c
> @@ -1222,8 +1222,7 @@ static void irs_map_l2_istr_write(GICv5 *s, GICv5Domain domain, uint64_t value)
>      uint64_t l1_iste;
>      MemTxResult res;
>  
> -    if (!FIELD_EX64(cs->irs_ist_baser[domain], IRS_IST_BASER, VALID) ||
> -        !cfg->structure) {
> +    if (!cfg->valid || !cfg->structure) {
>          /* WI if no IST set up or it is not 2-level */
>          return;
>      }
> @@ -1293,7 +1292,7 @@ static void irs_ist_baser_write(GICv5 *s, GICv5Domain domain, uint64_t value)
>  {
>      GICv5Common *cs = ARM_GICV5_COMMON(s);
>  
> -    if (FIELD_EX64(cs->irs_ist_baser[domain], IRS_IST_BASER, VALID)) {
> +    if (s->phys_lpi_config[domain].valid) {
>          /* If VALID is set, ADDR is RO and we can only update VALID */
>          bool valid = FIELD_EX64(value, IRS_IST_BASER, VALID);
>          if (valid) {
> @@ -1604,7 +1603,7 @@ static bool config_writel(GICv5 *s, GICv5Domain domain, hwaddr offset,
>                              deposit64(cs->irs_ist_baser[domain], 32, 32, data));
>          return true;
>      case A_IRS_IST_CFGR:
> -        if (FIELD_EX64(cs->irs_ist_baser[domain], IRS_IST_BASER, VALID)) {
> +        if (s->phys_lpi_config[domain].valid) {
>              qemu_log_mask(LOG_GUEST_ERROR,
>                            "guest tried to write IRS_IST_CFGR for %s config frame "
>                            "while IST_BASER.VALID set\n", domain_name[domain]);

That makes sense.

Reviewed-by: Jim MacArthur <jim.macarthur@linaro.org>