KVM: PPC: Handle some PAPR hcalls in the kernel

This adds the infrastructure for handling PAPR hcalls in the kernel,
either early in the guest exit path while we are still in real mode,
or later once the MMU has been turned back on and we are in the full
kernel context.  The advantage of handling hcalls in real mode if
possible is that we avoid two partition switches -- and this will
become more important when we support SMT4 guests, since a partition
switch means we have to pull all of the threads in the core out of
the guest.  The disadvantage is that we can only access the kernel
linear mapping, not anything vmalloced or ioremapped, since the MMU
is off.

This also adds code to handle the following hcalls in real mode:

H_ENTER       Add an HPTE to the hashed page table
H_REMOVE      Remove an HPTE from the hashed page table
H_READ        Read HPTEs from the hashed page table
H_PROTECT     Change the protection bits in an HPTE
H_BULK_REMOVE Remove up to 4 HPTEs from the hashed page table
H_SET_DABR    Set the data address breakpoint register

Plus code to handle the following hcalls in the kernel:

H_CEDE        Idle the vcpu until an interrupt or H_PROD hcall arrives
H_PROD        Wake up a ceded vcpu
H_REGISTER_VPA Register a virtual processor area (VPA)

The code that runs in real mode has to be in the base kernel, not in
the module, if KVM is compiled as a module.  The real-mode code can
only access the kernel linear mapping, not vmalloc or ioremap space.

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

1 files changed, 155 insertions, 3 deletions

diff --git a/arch/powerpc/kvm/book3s_hv_rmhandlers.S b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
index 9af264840b98..319ff63b1f31 100644
--- a/arch/powerpc/kvm/book3s_hv_rmhandlers.S
+++ b/arch/powerpc/kvm/book3s_hv_rmhandlers.S
@@ -166,6 +166,14 @@ kvmppc_hv_entry:
 	/* Save R1 in the PACA */
 	std	r1, HSTATE_HOST_R1(r13)
 
+	/* Increment yield count if they have a VPA */
+	ld	r3, VCPU_VPA(r4)
+	cmpdi	r3, 0
+	beq	25f
+	lwz	r5, LPPACA_YIELDCOUNT(r3)
+	addi	r5, r5, 1
+	stw	r5, LPPACA_YIELDCOUNT(r3)
+25:
 	/* Load up DAR and DSISR */
 	ld	r5, VCPU_DAR(r4)
 	lwz	r6, VCPU_DSISR(r4)
@@ -401,6 +409,10 @@ kvmppc_interrupt:
 	cmpwi	r3,0
 	bge	ignore_hdec
 2:
+	/* See if this is something we can handle in real mode */
+	cmpwi	r12,BOOK3S_INTERRUPT_SYSCALL
+	beq	hcall_try_real_mode
+hcall_real_cont:
 
 	/* Check for mediated interrupts (could be done earlier really ...) */
 	cmpwi	r12,BOOK3S_INTERRUPT_EXTERNAL
@@ -579,13 +591,28 @@ hdec_soon:
 	std	r5, VCPU_SPRG2(r9)
 	std	r6, VCPU_SPRG3(r9)
 
-	/* Save PMU registers */
+	/* Increment yield count if they have a VPA */
+	ld	r8, VCPU_VPA(r9)	/* do they have a VPA? */
+	cmpdi	r8, 0
+	beq	25f
+	lwz	r3, LPPACA_YIELDCOUNT(r8)
+	addi	r3, r3, 1
+	stw	r3, LPPACA_YIELDCOUNT(r8)
+25:
+	/* Save PMU registers if requested */
+	/* r8 and cr0.eq are live here */
 	li	r3, 1
 	sldi	r3, r3, 31		/* MMCR0_FC (freeze counters) bit */
 	mfspr	r4, SPRN_MMCR0		/* save MMCR0 */
 	mtspr	SPRN_MMCR0, r3		/* freeze all counters, disable ints */
 	isync
-	mfspr	r5, SPRN_MMCR1
+	beq	21f			/* if no VPA, save PMU stuff anyway */
+	lbz	r7, LPPACA_PMCINUSE(r8)
+	cmpwi	r7, 0			/* did they ask for PMU stuff to be saved? */
+	bne	21f
+	std	r3, VCPU_MMCR(r9)	/* if not, set saved MMCR0 to FC */
+	b	22f
+21:	mfspr	r5, SPRN_MMCR1
 	mfspr	r6, SPRN_MMCRA
 	std	r4, VCPU_MMCR(r9)
 	std	r5, VCPU_MMCR + 8(r9)
@@ -676,6 +703,125 @@ hdec_soon:
 	mfspr	r7,SPRN_HDSISR
 	b	7b
 
+/*
+ * Try to handle an hcall in real mode.
+ * Returns to the guest if we handle it, or continues on up to
+ * the kernel if we can't (i.e. if we don't have a handler for
+ * it, or if the handler returns H_TOO_HARD).
+ */
+	.globl	hcall_try_real_mode
+hcall_try_real_mode:
+	ld	r3,VCPU_GPR(r3)(r9)
+	andi.	r0,r11,MSR_PR
+	bne	hcall_real_cont
+	clrrdi	r3,r3,2
+	cmpldi	r3,hcall_real_table_end - hcall_real_table
+	bge	hcall_real_cont
+	LOAD_REG_ADDR(r4, hcall_real_table)
+	lwzx	r3,r3,r4
+	cmpwi	r3,0
+	beq	hcall_real_cont
+	add	r3,r3,r4
+	mtctr	r3
+	mr	r3,r9		/* get vcpu pointer */
+	ld	r4,VCPU_GPR(r4)(r9)
+	bctrl
+	cmpdi	r3,H_TOO_HARD
+	beq	hcall_real_fallback
+	ld	r4,HSTATE_KVM_VCPU(r13)
+	std	r3,VCPU_GPR(r3)(r4)
+	ld	r10,VCPU_PC(r4)
+	ld	r11,VCPU_MSR(r4)
+	b	fast_guest_return
+
+	/* We've attempted a real mode hcall, but it's punted it back
+	 * to userspace.  We need to restore some clobbered volatiles
+	 * before resuming the pass-it-to-qemu path */
+hcall_real_fallback:
+	li	r12,BOOK3S_INTERRUPT_SYSCALL
+	ld	r9, HSTATE_KVM_VCPU(r13)
+	ld	r11, VCPU_MSR(r9)
+
+	b	hcall_real_cont
+
+	.globl	hcall_real_table
+hcall_real_table:
+	.long	0		/* 0 - unused */
+	.long	.kvmppc_h_remove - hcall_real_table
+	.long	.kvmppc_h_enter - hcall_real_table
+	.long	.kvmppc_h_read - hcall_real_table
+	.long	0		/* 0x10 - H_CLEAR_MOD */
+	.long	0		/* 0x14 - H_CLEAR_REF */
+	.long	.kvmppc_h_protect - hcall_real_table
+	.long	0		/* 0x1c - H_GET_TCE */
+	.long	0		/* 0x20 - H_SET_TCE */
+	.long	0		/* 0x24 - H_SET_SPRG0 */
+	.long	.kvmppc_h_set_dabr - hcall_real_table
+	.long	0		/* 0x2c */
+	.long	0		/* 0x30 */
+	.long	0		/* 0x34 */
+	.long	0		/* 0x38 */
+	.long	0		/* 0x3c */
+	.long	0		/* 0x40 */
+	.long	0		/* 0x44 */
+	.long	0		/* 0x48 */
+	.long	0		/* 0x4c */
+	.long	0		/* 0x50 */
+	.long	0		/* 0x54 */
+	.long	0		/* 0x58 */
+	.long	0		/* 0x5c */
+	.long	0		/* 0x60 */
+	.long	0		/* 0x64 */
+	.long	0		/* 0x68 */
+	.long	0		/* 0x6c */
+	.long	0		/* 0x70 */
+	.long	0		/* 0x74 */
+	.long	0		/* 0x78 */
+	.long	0		/* 0x7c */
+	.long	0		/* 0x80 */
+	.long	0		/* 0x84 */
+	.long	0		/* 0x88 */
+	.long	0		/* 0x8c */
+	.long	0		/* 0x90 */
+	.long	0		/* 0x94 */
+	.long	0		/* 0x98 */
+	.long	0		/* 0x9c */
+	.long	0		/* 0xa0 */
+	.long	0		/* 0xa4 */
+	.long	0		/* 0xa8 */
+	.long	0		/* 0xac */
+	.long	0		/* 0xb0 */
+	.long	0		/* 0xb4 */
+	.long	0		/* 0xb8 */
+	.long	0		/* 0xbc */
+	.long	0		/* 0xc0 */
+	.long	0		/* 0xc4 */
+	.long	0		/* 0xc8 */
+	.long	0		/* 0xcc */
+	.long	0		/* 0xd0 */
+	.long	0		/* 0xd4 */
+	.long	0		/* 0xd8 */
+	.long	0		/* 0xdc */
+	.long	0		/* 0xe0 */
+	.long	0		/* 0xe4 */
+	.long	0		/* 0xe8 */
+	.long	0		/* 0xec */
+	.long	0		/* 0xf0 */
+	.long	0		/* 0xf4 */
+	.long	0		/* 0xf8 */
+	.long	0		/* 0xfc */
+	.long	0		/* 0x100 */
+	.long	0		/* 0x104 */
+	.long	0		/* 0x108 */
+	.long	0		/* 0x10c */
+	.long	0		/* 0x110 */
+	.long	0		/* 0x114 */
+	.long	0		/* 0x118 */
+	.long	0		/* 0x11c */
+	.long	0		/* 0x120 */
+	.long	.kvmppc_h_bulk_remove - hcall_real_table
+hcall_real_table_end:
+
 ignore_hdec:
 	mr	r4,r9
 	b	fast_guest_return
@@ -688,10 +834,16 @@ bounce_ext_interrupt:
 	LOAD_REG_IMMEDIATE(r11,MSR_SF | MSR_ME);
 	b	fast_guest_return
 
+_GLOBAL(kvmppc_h_set_dabr)
+	std	r4,VCPU_DABR(r3)
+	mtspr	SPRN_DABR,r4
+	li	r3,0
+	blr
+
 /*
  * Save away FP, VMX and VSX registers.
  * r3 = vcpu pointer
-*/
+ */
 _GLOBAL(kvmppc_save_fp)
 	mfmsr	r9
 	ori	r8,r9,MSR_FP