[PATCH v3 2/6] powerpc64/ftrace: Disable ftrace during kvm guest entry/exit
From: Naveen N. Rao <hidden>
Date: 2018-03-22 10:25:52
Subsystem:
kernel virtual machine for powerpc (kvm/powerpc), linux for powerpc (32-bit and 64-bit), the rest · Maintainers:
Madhavan Srinivasan, Michael Ellerman, Linus Torvalds
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_disabled. Once we exit the guest and restore host MMU context, we re-enable ftrace. Signed-off-by: Naveen N. Rao <redacted> --- 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 f31f357b8c5a..9292087adb68 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S@@ -600,6 +600,10 @@ 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, 1 + stb r6, PACA_FTRACE_DISABLED(r13) + li r6, KVM_GUEST_MODE_HOST_HV stb r6, HSTATE_IN_GUEST(r13)
@@ -2048,6 +2052,8 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX) /* Unset guest mode */ li r0, KVM_GUEST_MODE_NONE stb r0, HSTATE_IN_GUEST(r13) + li r0, 0 + stb r0, PACA_FTRACE_DISABLED(r13) ld r0, SFS+PPC_LR_STKOFF(r1) addi r1, r1, SFS
@@ -3379,6 +3385,8 @@ END_MMU_FTR_SECTION_IFSET(MMU_FTR_TYPE_RADIX) ld r8, KVM_HOST_LPCR(r10) mtspr SPRN_LPCR, r8 isync + li r0, 0 + stb r0, PACA_FTRACE_DISABLED(r13) li r0, KVM_GUEST_MODE_NONE stb r0, HSTATE_IN_GUEST(r13)
--
2.16.2