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@xxxxxxxxx>
--
It has always been possible to sreset the host with direct scom
access, but the patch e36d0a2ed5 has significantly expanded this
functionality so in practice this is a required as a fix for it.
Since RFC:
- Removed the last hunk as sugggested by Paul.
- Re-tested.
Thanks,
Nick
---
arch/powerpc/include/asm/hw_irq.h | 1 +
arch/powerpc/kernel/exceptions-64s.S | 2 ++
arch/powerpc/kernel/irq.c | 3 ++-
arch/powerpc/kvm/book3s_hv.c | 7 ++++++-
4 files changed, 11 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/asm/hw_irq.h
index 92a3e9a79cb4..a8bbac425ae6 100644
--- a/arch/powerpc/include/asm/hw_irq.h
+++ b/arch/powerpc/include/asm/hw_irq.h
@@ -40,6 +40,7 @@
#ifndef __ASSEMBLY__
+extern void replay_system_reset(void);
extern void __replay_interrupt(unsigned int vector);
extern void timer_interrupt(struct pt_regs *);
diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
index 651e1a0114ed..bff2ed6e3c3c 100644
--- a/arch/powerpc/kernel/exceptions-64s.S
+++ b/arch/powerpc/kernel/exceptions-64s.S
@@ -113,6 +113,7 @@ EXC_VIRT_NONE(0x4000, 0x100)
cmpwi cr3,r10,2 ; \
BRANCH_TO_C000(r10, system_reset_idle_common) ; \
1: \
+ KVMTEST_PR(n) ; \
END_FTR_SECTION_IFSET(CPU_FTR_HVMODE | CPU_FTR_ARCH_206)
#else
#define IDLETEST NOTEST
@@ -129,6 +130,7 @@ EXC_REAL_BEGIN(system_reset, 0x100, 0x100)
EXC_REAL_END(system_reset, 0x100, 0x100)
EXC_VIRT_NONE(0x4100, 0x100)
+TRAMP_KVM(PACA_EXNMI, 0x100)
#ifdef CONFIG_PPC_P7_NAP
EXC_COMMON_BEGIN(system_reset_idle_common)
diff --git a/arch/powerpc/kernel/irq.c b/arch/powerpc/kernel/irq.c
index efbadcbbf694..7e8259106944 100644
--- a/arch/powerpc/kernel/irq.c
+++ b/arch/powerpc/kernel/irq.c
@@ -437,7 +437,7 @@ static const u8 srr1_to_lazyirq[0x10] = {
PACA_IRQ_HMI,
0, 0, 0, 0, 0 };
-static noinline void replay_system_reset(void)
+void replay_system_reset(void)
{
struct pt_regs regs;
@@ -447,6 +447,7 @@ static noinline void replay_system_reset(void)
system_reset_exception(®s);
get_paca()->in_nmi = 0;
}
+EXPORT_SYMBOL_GPL(replay_system_reset);
void irq_set_pending_from_srr1(unsigned long srr1)
{
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 8f34715cfbff..31a362669fea 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;
}
}
--
2.15.0
--
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