During guest entry/exit, we switch over to/from the guest MMU context.
While doing so, we set our state to KVM_GUEST_MODE_HOST_HV to note down
the fact that we cannot take any exceptions in the hypervisor code.
Since ftrace may be enabled and since it can result in us taking a trap,
disable ftrace by setting paca->ftrace_enabled to zero. Once we exit the
guest and restore host MMU context, we re-enable ftrace.
Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
---
arch/powerpc/kvm/book3s_hv_rmhandlers.S | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index bd63fa8a08b5..6f2d7206a12b 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -598,6 +598,10 @@ kvmppc_hv_entry:
/* Save R1 in the PACA */
std r1, HSTATE_HOST_R1(r13)
+ /* Disable ftrace since we can't take a trap any more */
+ li r6, 0
+ stb r6, PACA_FTRACE_ENABLED(r13)
+
li r6, KVM_GUEST_MODE_HOST_HV
stb r6, HSTATE_IN_GUEST(r13)
@@ -2078,6 +2082,8 @@ END_FTR_SECTION_IFSET(CPU_FTR_ARCH_300)
/* Unset guest mode */
li r0, KVM_GUEST_MODE_NONE
stb r0, HSTATE_IN_GUEST(r13)
+ li r0, 1
+ stb r0, PACA_FTRACE_ENABLED(r13)
lwz r12, STACK_SLOT_TRAP(r1) /* return trap # in r12 */
ld r0, SFS+PPC_LR_STKOFF(r1)
@@ -3547,6 +3553,8 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX)
ld r8, KVM_HOST_LPCR(r10)
mtspr SPRN_LPCR, r8
isync
+ li r0, 1
+ stb r0, PACA_FTRACE_ENABLED(r13)
li r0, KVM_GUEST_MODE_NONE
stb r0, HSTATE_IN_GUEST(r13)
--
2.16.2
