KVM: PPC: book3s_pr: Simplify transitions between virtual and real mode

This simplifies the way that the book3s_pr makes the transition to
real mode when entering the guest.  We now call kvmppc_entry_trampoline
(renamed from kvmppc_rmcall) in the base kernel using a normal function
call instead of doing an indirect call through a pointer in the vcpu.
If kvm is a module, the module loader takes care of generating a
trampoline as it does for other calls to functions outside the module.

kvmppc_entry_trampoline then disables interrupts and jumps to
kvmppc_handler_trampoline_enter in real mode using an rfi[d].
That then uses the link register as the address to return to
(potentially in module space) when the guest exits.

This also simplifies the way that we call the Linux interrupt handler
when we exit the guest due to an external, decrementer or performance
monitor interrupt.  Instead of turning on the MMU, then deciding that
we need to call the Linux handler and turning the MMU back off again,
we now go straight to the handler at the point where we would turn the
MMU on.  The handler will then return to the virtual-mode code
(potentially in the module).

Along the way, this moves the setting and clearing of the HID5 DCBZ32
bit into real-mode interrupts-off code, and also makes sure that
we clear the MSR[RI] bit before loading values into SRR0/1.

The net result is that we no longer need any code addresses to be
stored in vcpu->arch.

Signed-off-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Alexander Graf <agraf@suse.de>

1 files changed, 17 insertions, 34 deletions

diff --git a/arch/powerpc/kvm/book3s_rmhandlers.S b/arch/powerpc/kvm/book3s_rmhandlers.S
index 5ee66edd749..34187585c50 100644
--- a/arch/powerpc/kvm/book3s_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_rmhandlers.S
@@ -36,9 +36,8 @@
 
 #if defined(CONFIG_PPC_BOOK3S_64)
 
-#define LOAD_SHADOW_VCPU(reg)	GET_PACA(reg)					
-#define MSR_NOIRQ		MSR_KERNEL & ~(MSR_IR | MSR_DR)
 #define FUNC(name) 		GLUE(.,name)
+#define MTMSR_EERI(reg)		mtmsrd	(reg),1
 
 	.globl	kvmppc_skip_interrupt
 kvmppc_skip_interrupt:
@@ -68,8 +67,8 @@ kvmppc_skip_Hinterrupt:
 
 #elif defined(CONFIG_PPC_BOOK3S_32)
 
-#define MSR_NOIRQ		MSR_KERNEL
 #define FUNC(name)		name
+#define MTMSR_EERI(reg)		mtmsr	(reg)
 
 .macro INTERRUPT_TRAMPOLINE intno
 
@@ -170,40 +169,24 @@ kvmppc_handler_skip_ins:
 #endif
 
 /*
- * This trampoline brings us back to a real mode handler
- *
- * Input Registers:
- *
- * R5 = SRR0
- * R6 = SRR1
- * LR = real-mode IP
+ * Call kvmppc_handler_trampoline_enter in real mode
  *
+ * On entry, r4 contains the guest shadow MSR
  */
-.global kvmppc_handler_lowmem_trampoline
-kvmppc_handler_lowmem_trampoline:
-
-	mtsrr0	r5
+_GLOBAL(kvmppc_entry_trampoline)
+	mfmsr	r5
+	LOAD_REG_ADDR(r7, kvmppc_handler_trampoline_enter)
+	toreal(r7)
+
+	li	r9, MSR_RI
+	ori	r9, r9, MSR_EE
+	andc	r9, r5, r9	/* Clear EE and RI in MSR value */
+	li	r6, MSR_IR | MSR_DR
+	ori	r6, r6, MSR_EE
+	andc	r6, r5, r6	/* Clear EE, DR and IR in MSR value */
+	MTMSR_EERI(r9)		/* Clear EE and RI in MSR */
+	mtsrr0	r7		/* before we set srr0/1 */
 	mtsrr1	r6
-	blr
-kvmppc_handler_lowmem_trampoline_end:
-
-/*
- * Call a function in real mode
- *
- * Input Registers:
- *
- * R3 = function
- * R4 = MSR
- * R5 = scratch register
- *
- */
-_GLOBAL(kvmppc_rmcall)
-	LOAD_REG_IMMEDIATE(r5, MSR_NOIRQ)
-	mtmsr	r5		/* Disable relocation and interrupts, so mtsrr
-				   doesn't get interrupted */
-	sync
-	mtsrr0	r3
-	mtsrr1	r4
 	RFI
 
 #if defined(CONFIG_PPC_BOOK3S_32)