+++ /dev/null
-From a3bf9fbdad600b1e4335dd90979f8d6072e4f602 Mon Sep 17 00:00:00 2001
-From: Greg Kurz <groug@kaod.org>
-Date: Wed, 15 May 2019 12:05:01 +0200
-Subject: powerpc/pseries: Fix xive=off command line
-MIME-Version: 1.0
-Content-Type: text/plain; charset=UTF-8
-Content-Transfer-Encoding: 8bit
-
-From: Greg Kurz <groug@kaod.org>
-
-commit a3bf9fbdad600b1e4335dd90979f8d6072e4f602 upstream.
-
-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>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
----
- arch/powerpc/kernel/prom_init.c | 16 +++++++++++-
- arch/powerpc/sysdev/xive/spapr.c | 52 ++++++++++++++++++++++++++++++++++++++-
- 2 files changed, 66 insertions(+), 2 deletions(-)
-
---- a/arch/powerpc/kernel/prom_init.c
-+++ b/arch/powerpc/kernel/prom_init.c
-@@ -174,6 +174,7 @@ static unsigned long __prombss prom_tce_
-
- #ifdef CONFIG_PPC_PSERIES
- static bool __prombss prom_radix_disable;
-+static bool __prombss prom_xive_disable;
- #endif
-
- struct platform_support {
-@@ -684,6 +685,12 @@ static void __init early_cmdline_parse(v
- }
- 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 */
- }
-
-@@ -1092,10 +1099,17 @@ static void __init prom_parse_xive_model
- 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 */
---- a/arch/powerpc/sysdev/xive/spapr.c
-+++ b/arch/powerpc/sysdev/xive/spapr.c
-@@ -20,6 +20,7 @@
- #include <linux/cpumask.h>
- #include <linux/mm.h>
- #include <linux/delay.h>
-+#include <linux/libfdt.h>
-
- #include <asm/prom.h>
- #include <asm/io.h>
-@@ -663,6 +664,55 @@ static bool xive_get_max_prio(u8 *max_pr
- 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;
-@@ -675,7 +725,7 @@ bool __init xive_spapr_init(void)
- const __be32 *reg;
- int i;
-
-- if (xive_cmdline_disabled)
-+ if (xive_spapr_disabled())
- return false;
-
- pr_devel("%s()\n", __func__);
projects / thirdparty / kernel / stable-queue.git / commitdiff
