[PATCH 4.9 052/130] powerpc/icp-opal: Fix missing KVM case and harden replay

[Greg Kroah-Hartman]

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Benjamin Herrenschmidt <b...@kernel.crashing.org>

commit 9728a7c8ab2f7a1c8d5c95278d2e4f4ac1285385 upstream.

The icp-opal call is missing the code from icp-native to recover
interrupts snatched by KVM. Without that, when running KVM, we can
get into a situation where an interrupt is lost and the CPU stuck
with an elevated CPPR.

Also harden replay by always checking the return from opal_int_eoi().

Fixes: d74361881f0d ("powerpc/xics: Add ICP OPAL backend")
Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/powerpc/sysdev/xics/icp-opal.c |   31 ++++++++++++++++++++++++-------
 1 file changed, 24 insertions(+), 7 deletions(-)

--- a/arch/powerpc/sysdev/xics/icp-opal.c
+++ b/arch/powerpc/sysdev/xics/icp-opal.c
@@ -20,6 +20,7 @@
 #include <asm/xics.h>
 #include <asm/io.h>
 #include <asm/opal.h>
+#include <asm/kvm_ppc.h>
 
 static void icp_opal_teardown_cpu(void)
 {
@@ -39,7 +40,26 @@ static void icp_opal_flush_ipi(void)
         * Should we be flagging idle loop instead?
         * Or creating some task to be scheduled?
         */
-       opal_int_eoi((0x00 << 24) | XICS_IPI);
+       if (opal_int_eoi((0x00 << 24) | XICS_IPI) > 0)
+               force_external_irq_replay();
+}
+
+static unsigned int icp_opal_get_xirr(void)
+{
+       unsigned int kvm_xirr;
+       __be32 hw_xirr;
+       int64_t rc;
+
+       /* Handle an interrupt latched by KVM first */
+       kvm_xirr = kvmppc_get_xics_latch();
+       if (kvm_xirr)
+               return kvm_xirr;
+
+       /* Then ask OPAL */
+       rc = opal_int_get_xirr(&hw_xirr, false);
+       if (rc < 0)
+               return 0;
+       return be32_to_cpu(hw_xirr);
 }
 
 static unsigned int icp_opal_get_irq(void)
@@ -47,12 +67,8 @@ static unsigned int icp_opal_get_irq(voi
        unsigned int xirr;
        unsigned int vec;
        unsigned int irq;
-       int64_t rc;
 
-       rc = opal_int_get_xirr(&xirr, false);
-       if (rc < 0)
-               return 0;
-       xirr = be32_to_cpu(xirr);
+       xirr = icp_opal_get_xirr();
        vec = xirr & 0x00ffffff;
        if (vec == XICS_IRQ_SPURIOUS)
                return 0;
@@ -67,7 +83,8 @@ static unsigned int icp_opal_get_irq(voi
        xics_mask_unknown_vec(vec);
 
        /* We might learn about it later, so EOI it */
-       opal_int_eoi(xirr);
+       if (opal_int_eoi(xirr) > 0)
+               force_external_irq_replay();
 
        return 0;
 }