commit 6de6638b35daa0dfb7daefd78d55015655b4d8f3
author Nicholas Piggin <npiggin@gmail.com> Sun Nov 05 23:33:55 2017 +1100
committer Michael Ellerman <mpe@ellerman.id.au> Mon Nov 06 16:48:06 2017 +1100
tree b0a12166cb417561a7bbaf14bbd8d4b30d7bbbc5
parent 4dd9eab39c71628d113168a01473ee17b5f61eac

KVM: PPC: Book3S HV: Handle host system reset in guest mode

If the host takes a system reset interrupt while a guest is running,
the CPU must exit the guest before processing the host exception
handler.

After this patch, taking a sysrq+x with a CPU running in a guest
gives a trace like this:

   cpu 0x27: Vector: 100 (System Reset) at [c000000fdf5776f0]
       pc: c008000010158b80: kvmppc_run_core+0x16b8/0x1ad0 [kvm_hv]
       lr: c008000010158b80: kvmppc_run_core+0x16b8/0x1ad0 [kvm_hv]
       sp: c000000fdf577850
      msr: 9000000002803033
     current = 0xc000000fdf4b1e00
     paca    = 0xc00000000fd4d680	 softe: 3	 irq_happened: 0x01
       pid   = 6608, comm = qemu-system-ppc
   Linux version 4.14.0-rc7-01489-g47e1893a404a-dirty #26 SMP
   [c000000fdf577a00] c008000010159dd4 kvmppc_vcpu_run_hv+0x3dc/0x12d0 [kvm_hv]
   [c000000fdf577b30] c0080000100a537c kvmppc_vcpu_run+0x44/0x60 [kvm]
   [c000000fdf577b60] c0080000100a1ae0 kvm_arch_vcpu_ioctl_run+0x118/0x310 [kvm]
   [c000000fdf577c00] c008000010093e98 kvm_vcpu_ioctl+0x530/0x7c0 [kvm]
   [c000000fdf577d50] c000000000357bf8 do_vfs_ioctl+0xd8/0x8c0
   [c000000fdf577df0] c000000000358448 SyS_ioctl+0x68/0x100
   [c000000fdf577e30] c00000000000b220 system_call+0x58/0x6c
   --- Exception: c01 (System Call) at 00007fff76868df0
   SP (7fff7069baf0) is in userspace

Fixes: e36d0a2ed5 ("powerpc/powernv: Implement NMI IPI with OPAL_SIGNAL_SYSTEM_RESET")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kvm/book3s_hv.c

diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 8f34715..31a3626 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -47,6 +47,7 @@
 
 #include <asm/reg.h>
 #include <asm/ppc-opcode.h>
+#include <asm/asm-prototypes.h>
 #include <asm/disassemble.h>
 #include <asm/cputable.h>
 #include <asm/cacheflush.h>
@@ -1089,9 +1090,10 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
 		vcpu->stat.ext_intr_exits++;
 		r = RESUME_GUEST;
 		break;
-	/* HMI is hypervisor interrupt and host has handled it. Resume guest.*/
+	/* SR/HMI/PMI are HV interrupts that host has handled. Resume guest.*/
 	case BOOK3S_INTERRUPT_HMI:
 	case BOOK3S_INTERRUPT_PERFMON:
+	case BOOK3S_INTERRUPT_SYSTEM_RESET:
 		r = RESUME_GUEST;
 		break;
 	case BOOK3S_INTERRUPT_MACHINE_CHECK:
@@ -2604,6 +2606,9 @@ static void set_irq_happened(int trap)
 	case BOOK3S_INTERRUPT_HMI:
 		local_paca->irq_happened |= PACA_IRQ_HMI;
 		break;
+	case BOOK3S_INTERRUPT_SYSTEM_RESET:
+		replay_system_reset();
+		break;
 	}
 }