On POWER9, if the hypervisor supports XIVE exploitation mode, the
guest OS will unconditionally requests for the XIVE interrupt mode
even if XIVE was deactivated with the kernel command line xive=off.
Later on, when the spapr XIVE init code handles xive=off, it disables
XIVE and tries to fall back on the legacy mode XICS.
This discrepency causes a kernel panic because the hypervisor is
configured to provide the XIVE interrupt mode to the guest :
kernel BUG at arch/powerpc/sysdev/xics/xics-common.c:135!
...
NIP xics_smp_probe+0x38/0x98
LR xics_smp_probe+0x2c/0x98
Call Trace:
xics_smp_probe+0x2c/0x98 (unreliable)
pSeries_smp_probe+0x40/0xa0
smp_prepare_cpus+0x62c/0x6ec
kernel_init_freeable+0x148/0x448
kernel_init+0x2c/0x148
ret_from_kernel_thread+0x5c/0x68
Look for xive=off during prom_init and don't ask for XIVE in this
case. One exception though: if the host only supports XIVE, we still
want to boot so we ignore xive=off.
Similarly, have the spapr XIVE init code to looking at the interrupt
mode negotiated during CAS, and ignore xive=off if the hypervisor only
supports XIVE.
Fixes:
eac1e731b59e ("powerpc/xive: guest exploitation of the XIVE interrupt controller")
Cc: stable@vger.kernel.org # v4.20
Reported-by: Pavithra R. Prakash <pavrampu@in.ibm.com>
Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
#ifdef CONFIG_PPC_PSERIES
static bool __prombss prom_radix_disable;
+static bool __prombss prom_xive_disable;
#endif
struct platform_support {
}
if (prom_radix_disable)
prom_debug("Radix disabled from cmdline\n");
+
+ opt = prom_strstr(prom_cmd_line, "xive=off");
+ if (opt) {
+ prom_xive_disable = true;
+ prom_debug("XIVE disabled from cmdline\n");
+ }
#endif /* CONFIG_PPC_PSERIES */
}
switch (val) {
case OV5_FEAT(OV5_XIVE_EITHER): /* Either Available */
prom_debug("XIVE - either mode supported\n");
- support->xive = true;
+ support->xive = !prom_xive_disable;
break;
case OV5_FEAT(OV5_XIVE_EXPLOIT): /* Only Exploitation mode */
prom_debug("XIVE - exploitation mode supported\n");
+ if (prom_xive_disable) {
+ /*
+ * If we __have__ to do XIVE, we're better off ignoring
+ * the command line rather than not booting.
+ */
+ prom_printf("WARNING: Ignoring cmdline option xive=off\n");
+ }
support->xive = true;
break;
case OV5_FEAT(OV5_XIVE_LEGACY): /* Only Legacy mode */
#include <linux/cpumask.h>
#include <linux/mm.h>
#include <linux/delay.h>
+#include <linux/libfdt.h>
#include <asm/prom.h>
#include <asm/io.h>
return true;
}
+static const u8 *get_vec5_feature(unsigned int index)
+{
+ unsigned long root, chosen;
+ int size;
+ const u8 *vec5;
+
+ root = of_get_flat_dt_root();
+ chosen = of_get_flat_dt_subnode_by_name(root, "chosen");
+ if (chosen == -FDT_ERR_NOTFOUND)
+ return NULL;
+
+ vec5 = of_get_flat_dt_prop(chosen, "ibm,architecture-vec-5", &size);
+ if (!vec5)
+ return NULL;
+
+ if (size <= index)
+ return NULL;
+
+ return vec5 + index;
+}
+
+static bool xive_spapr_disabled(void)
+{
+ const u8 *vec5_xive;
+
+ vec5_xive = get_vec5_feature(OV5_INDX(OV5_XIVE_SUPPORT));
+ if (vec5_xive) {
+ u8 val;
+
+ val = *vec5_xive & OV5_FEAT(OV5_XIVE_SUPPORT);
+ switch (val) {
+ case OV5_FEAT(OV5_XIVE_EITHER):
+ case OV5_FEAT(OV5_XIVE_LEGACY):
+ break;
+ case OV5_FEAT(OV5_XIVE_EXPLOIT):
+ /* Hypervisor only supports XIVE */
+ if (xive_cmdline_disabled)
+ pr_warn("WARNING: Ignoring cmdline option xive=off\n");
+ return false;
+ default:
+ pr_warn("%s: Unknown xive support option: 0x%x\n",
+ __func__, val);
+ break;
+ }
+ }
+
+ return xive_cmdline_disabled;
+}
+
bool __init xive_spapr_init(void)
{
struct device_node *np;
const __be32 *reg;
int i;
- if (xive_cmdline_disabled)
+ if (xive_spapr_disabled())
return false;
pr_devel("%s()\n", __func__);