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hw/intc/arm_gicv3_cpuif: handle LPIs in in the list registers 

The hypervisor can deliver (virtual) LPIs to a guest by setting up a
list register to have an intid which is an LPI.  The GIC has to treat
these a little differently to standard interrupt IDs, because LPIs
have no Active state, and so the guest will only EOI them, it will
not also deactivate them.  So icv_eoir_write() must do two things:

 * if the LPI ID is not in any list register, we drop the
   priority but do not increment the EOI count
 * if the LPI ID is in a list register, we immediately deactivate
   it, regardless of the split-drop-and-deactivate control

This can be seen in the VirtualWriteEOIR0() and VirtualWriteEOIR1()
pseudocode in the GICv3 architecture specification.

Without this fix, potentially a hypervisor guest might stall because
LPIs get stuck in a bogus Active+Pending state.

Cc: qemu-stable@nongnu.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Tested-by: Miguel Luis <miguel.luis@oracle.com>
This commit is contained in:
Peter Maydell 2024-01-09 14:43:44 +00:00
parent 3d65b958c5
commit 82a65e3188
1 changed files with 13 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
hw/intc/arm_gicv3_cpuif.c
View File

@ -1434,16 +1434,25 @@ static void icv_eoir_write(CPUARMState *env, const ARMCPRegInfo *ri,
idx = icv_find_active(cs, irq);
if (idx < 0) {
/* No valid list register corresponding to EOI ID */
icv_increment_eoicount(cs);
/*
* No valid list register corresponding to EOI ID; if this is a vLPI
* not in the list regs then do nothing; otherwise increment EOI count
*/
if (irq < GICV3_LPI_INTID_START) {
icv_increment_eoicount(cs);
}
} else {
uint64_t lr = cs->ich_lr_el2[idx];
int thisgrp = (lr & ICH_LR_EL2_GROUP) ? GICV3_G1NS : GICV3_G0;
int lr_gprio = ich_lr_prio(lr) & icv_gprio_mask(cs, grp);
if (thisgrp == grp && lr_gprio == dropprio) {
if (!icv_eoi_split(env, cs)) {
/* Priority drop and deactivate not split: deactivate irq now */
if (!icv_eoi_split(env, cs) || irq >= GICV3_LPI_INTID_START) {
/*
* Priority drop and deactivate not split: deactivate irq now.
* LPIs always get their active state cleared immediately
* because no separate deactivate is expected.
*/
icv_deactivate_irq(cs, idx);
}
}