From: Cédric Le Goater clg@kaod.org
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
--- arch/powerpc/sysdev/xive/common.c | 12 +++--------- arch/powerpc/sysdev/xive/native.c | 4 ++-- arch/powerpc/sysdev/xive/spapr.c | 4 ++-- arch/powerpc/sysdev/xive/xive-internal.h | 7 +++++++ 4 files changed, 14 insertions(+), 13 deletions(-)
--- 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 i 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(unsigne /* 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 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; } --- 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 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 msleep(1); continue; } - xc->hw_ipi = 0; + xc->hw_ipi = XIVE_BAD_IRQ; break; } } --- 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 i
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 */
--- 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