powerpc/xive: Use XIVE_BAD_IRQ instead of zero to catch non configured IPIs

commit b1a504a6500df50e83b701b7946b34fce27ad8a3 upstream.

When a CPU is brought up, an IPI number is allocated and recorded
under the XIVE CPU structure. Invalid IPI numbers are tracked with
interrupt number 0x0.

On the PowerNV platform, the interrupt number space starts at 0x10 and
this works fine. However, on the sPAPR platform, it is possible to
allocate the interrupt number 0x0 and this raises an issue when CPU 0
is unplugged. The XIVE spapr driver tracks allocated interrupt numbers
in a bitmask and it is not correctly updated when interrupt number 0x0
is freed. It stays allocated and it is then impossible to reallocate.

Fix by using the XIVE_BAD_IRQ value instead of zero on both platforms.

Reported-by: David Gibson <david@gibson.dropbear.id.au>
Fixes: eac1e731b59e ("powerpc/xive: guest exploitation of the XIVE interrupt controller")
Cc: stable@vger.kernel.org # v4.14+
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Tested-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200306150143.5551-2-clg@kaod.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/powerpc/sysdev/xive/common.c b/arch/powerpc/sysdev/xive/common.c
index a820370883d9348c6fa43835b0e6f821f9cb3fc7..b7ae5a027714eabb75002033d431d195b0e13443 100644 (file)
--- a/arch/powerpc/sysdev/xive/common.c
+++ b/arch/powerpc/sysdev/xive/common.c
@@ -72,13 +72,6 @@ static u32 xive_ipi_irq;
 /* Xive state for each CPU */
 static DEFINE_PER_CPU(struct xive_cpu *, xive_cpu);
 
-/*
- * A "disabled" interrupt should never fire, to catch problems
- * we set its logical number to this
- */
-#define XIVE_BAD_IRQ           0x7fffffff
-#define XIVE_MAX_IRQ           (XIVE_BAD_IRQ - 1)
-
 /* An invalid CPU target */
 #define XIVE_INVALID_TARGET    (-1)
 
@@ -1073,7 +1066,7 @@ static int xive_setup_cpu_ipi(unsigned int cpu)
        xc = per_cpu(xive_cpu, cpu);
 
        /* Check if we are already setup */
-       if (xc->hw_ipi != 0)
+       if (xc->hw_ipi != XIVE_BAD_IRQ)
                return 0;
 
        /* Grab an IPI from the backend, this will populate xc->hw_ipi */
@@ -1110,7 +1103,7 @@ static void xive_cleanup_cpu_ipi(unsigned int cpu, struct xive_cpu *xc)
        /* Disable the IPI and free the IRQ data */
 
        /* Already cleaned up ? */
-       if (xc->hw_ipi == 0)
+       if (xc->hw_ipi == XIVE_BAD_IRQ)
                return;
 
        /* Mask the IPI */
@@ -1266,6 +1259,7 @@ static int xive_prepare_cpu(unsigned int cpu)
                if (np)
                        xc->chip_id = of_get_ibm_chip_id(np);
                of_node_put(np);
+               xc->hw_ipi = XIVE_BAD_IRQ;
 
                per_cpu(xive_cpu, cpu) = xc;
        }

diff --git a/arch/powerpc/sysdev/xive/native.c b/arch/powerpc/sysdev/xive/native.c
index aac61374afebf581cae336b2de48f277f5a5ed8e..30cdcbfa1c04e519720d802194b53330700981eb 100644 (file)
--- a/arch/powerpc/sysdev/xive/native.c
+++ b/arch/powerpc/sysdev/xive/native.c
@@ -310,7 +310,7 @@ static void xive_native_put_ipi(unsigned int cpu, struct xive_cpu *xc)
        s64 rc;
 
        /* Free the IPI */
-       if (!xc->hw_ipi)
+       if (xc->hw_ipi == XIVE_BAD_IRQ)
                return;
        for (;;) {
                rc = opal_xive_free_irq(xc->hw_ipi);
@@ -318,7 +318,7 @@ static void xive_native_put_ipi(unsigned int cpu, struct xive_cpu *xc)
                        msleep(1);
                        continue;
                }
-               xc->hw_ipi = 0;
+               xc->hw_ipi = XIVE_BAD_IRQ;
                break;
        }
 }

diff --git a/arch/powerpc/sysdev/xive/spapr.c b/arch/powerpc/sysdev/xive/spapr.c
index 7fc41bf30fd594f1c7d9515cf40c2de833e89828..10235098a726660c97eee2c9c7f618487acce0d1 100644 (file)
--- a/arch/powerpc/sysdev/xive/spapr.c
+++ b/arch/powerpc/sysdev/xive/spapr.c
@@ -443,11 +443,11 @@ static int xive_spapr_get_ipi(unsigned int cpu, struct xive_cpu *xc)
 
 static void xive_spapr_put_ipi(unsigned int cpu, struct xive_cpu *xc)
 {
-       if (!xc->hw_ipi)
+       if (xc->hw_ipi == XIVE_BAD_IRQ)
                return;
 
        xive_irq_bitmap_free(xc->hw_ipi);
-       xc->hw_ipi = 0;
+       xc->hw_ipi = XIVE_BAD_IRQ;
 }
 #endif /* CONFIG_SMP */
 

diff --git a/arch/powerpc/sysdev/xive/xive-internal.h b/arch/powerpc/sysdev/xive/xive-internal.h
index f34abed0c05fd3064bf0a2c45fb193b49079283f..48808dbb25dce60df08cf38ae7456619338c26cb 100644 (file)
--- a/arch/powerpc/sysdev/xive/xive-internal.h
+++ b/arch/powerpc/sysdev/xive/xive-internal.h
@@ -9,6 +9,13 @@
 #ifndef __XIVE_INTERNAL_H
 #define __XIVE_INTERNAL_H
 
+/*
+ * A "disabled" interrupt should never fire, to catch problems
+ * we set its logical number to this
+ */
+#define XIVE_BAD_IRQ           0x7fffffff
+#define XIVE_MAX_IRQ           (XIVE_BAD_IRQ - 1)
+
 /* Each CPU carry one of these with various per-CPU state */
 struct xive_cpu {
 #ifdef CONFIG_SMP