KVM: PPC: Book3S HV: Add support for DABRX register on POWER7

The DABRX (DABR extension) register on POWER7 processors provides finer
control over which accesses cause a data breakpoint interrupt. It
contains 3 bits which indicate whether to enable accesses in user,
kernel and hypervisor modes respectively to cause data breakpoint
interrupts, plus one bit that enables both real mode and virtual mode
accesses to cause interrupts. Currently, KVM sets DABRX to allow
both kernel and user accesses to cause interrupts while in the guest.

This adds support for the guest to specify other values for DABRX.
PAPR defines a H_SET_XDABR hcall to allow the guest to set both DABR
and DABRX with one call. This adds a real-mode implementation of
H_SET_XDABR, which shares most of its code with the existing H_SET_DABR
implementation. To support this, we add a per-vcpu field to store the
DABRX value plus code to get and set it via the ONE_REG interface.

For Linux guests to use this new hcall, userspace needs to add
"hcall-xdabr" to the set of strings in the /chosen/hypertas-functions
property in the device tree. If userspace does this and then migrates
the guest to a host where the kernel doesn't include this patch, then
userspace will need to implement H_SET_XDABR by writing the specified
DABR value to the DABR using the ONE_REG interface. In that case, the
old kernel will set DABRX to DABRX_USER | DABRX_KERNEL. That should
still work correctly, at least for Linux guests, since Linux guests
cope with getting data breakpoint interrupts in modes that weren't
requested by just ignoring the interrupt, and Linux guests never set
DABRX_BTI.

The other thing this does is to make H_SET_DABR and H_SET_XDABR work
on POWER8, which has the DAWR and DAWRX instead of DABR/X. Guests that
know about POWER8 should use H_SET_MODE rather than H_SET_[X]DABR, but
guests running in POWER7 compatibility mode will still use H_SET_[X]DABR.
For them, this adds the logic to convert DABR/X values into DAWR/X values
on POWER8.

Signed-off-by: Paul Mackerras <[e-mail]>
Signed-off-by: Alexander Graf <[e-mail]>

Documentation/virtual/kvm/api.txt

···
   PPC   | KVM_REG_PPC_LPCR	| 64
   PPC   | KVM_REG_PPC_PPR	| 64
   PPC   | KVM_REG_PPC_ARCH_COMPAT 32
+  PPC   | KVM_REG_PPC_DABRX     | 32
   PPC   | KVM_REG_PPC_TM_GPR0	| 64
           ...
   PPC   | KVM_REG_PPC_TM_GPR31	| 64

arch/powerpc/include/asm/kvm_host.h

···
 	ulong uamor;
 	ulong iamr;
 	u32 ctrl;
+	u32 dabrx;
 	ulong dabr;
 	ulong dawr;
 	ulong dawrx;

arch/powerpc/include/asm/reg.h

···
 #define   CIABR_PRIV_SUPER	2
 #define   CIABR_PRIV_HYPER	3
 #define SPRN_DAWRX	0xBC
-#define   DAWRX_USER	(1UL << 0)
-#define   DAWRX_KERNEL	(1UL << 1)
-#define   DAWRX_HYP	(1UL << 2)
+#define   DAWRX_USER	__MASK(0)
+#define   DAWRX_KERNEL	__MASK(1)
+#define   DAWRX_HYP	__MASK(2)
+#define   DAWRX_WTI	__MASK(3)
+#define   DAWRX_WT	__MASK(4)
+#define   DAWRX_DR	__MASK(5)
+#define   DAWRX_DW	__MASK(6)
 #define SPRN_DABR	0x3F5	/* Data Address Breakpoint Register */
 #define SPRN_DABR2	0x13D	/* e300 */
 #define SPRN_DABRX	0x3F7	/* Data Address Breakpoint Register Extension */
-#define   DABRX_USER	(1UL << 0)
-#define   DABRX_KERNEL	(1UL << 1)
-#define   DABRX_HYP	(1UL << 2)
-#define   DABRX_BTI	(1UL << 3)
+#define   DABRX_USER	__MASK(0)
+#define   DABRX_KERNEL	__MASK(1)
+#define   DABRX_HYP	__MASK(2)
+#define   DABRX_BTI	__MASK(3)
 #define   DABRX_ALL     (DABRX_BTI | DABRX_HYP | DABRX_KERNEL | DABRX_USER)
 #define SPRN_DAR	0x013	/* Data Address Register */
 #define SPRN_DBCR	0x136	/* e300 Data Breakpoint Control Reg */

arch/powerpc/include/uapi/asm/kvm.h

···
 /* Architecture compatibility level */
 #define KVM_REG_PPC_ARCH_COMPAT	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb7)
 
+#define KVM_REG_PPC_DABRX	(KVM_REG_PPC | KVM_REG_SIZE_U32 | 0xb8)
+
 /* Transactional Memory checkpointed state:
  * This is all GPRs, all VSX regs and a subset of SPRs
  */

arch/powerpc/kernel/asm-offsets.c

···
 	DEFINE(VCPU_IAMR, offsetof(struct kvm_vcpu, arch.iamr));
 	DEFINE(VCPU_CTRL, offsetof(struct kvm_vcpu, arch.ctrl));
 	DEFINE(VCPU_DABR, offsetof(struct kvm_vcpu, arch.dabr));
+	DEFINE(VCPU_DABRX, offsetof(struct kvm_vcpu, arch.dabrx));
 	DEFINE(VCPU_DAWR, offsetof(struct kvm_vcpu, arch.dawr));
 	DEFINE(VCPU_DAWRX, offsetof(struct kvm_vcpu, arch.dawrx));
 	DEFINE(VCPU_CIABR, offsetof(struct kvm_vcpu, arch.ciabr));

arch/powerpc/kvm/book3s_hv.c

···
 	case KVM_REG_PPC_DABR:
 		*val = get_reg_val(id, vcpu->arch.dabr);
 		break;
+	case KVM_REG_PPC_DABRX:
+		*val = get_reg_val(id, vcpu->arch.dabrx);
+		break;
 	case KVM_REG_PPC_DSCR:
 		*val = get_reg_val(id, vcpu->arch.dscr);
 		break;
···
 		break;
 	case KVM_REG_PPC_DABR:
 		vcpu->arch.dabr = set_reg_val(id, *val);
+		break;
+	case KVM_REG_PPC_DABRX:
+		vcpu->arch.dabrx = set_reg_val(id, *val) & ~DABRX_HYP;
 		break;
 	case KVM_REG_PPC_DSCR:
 		vcpu->arch.dscr = set_reg_val(id, *val);

arch/powerpc/kvm/book3s_hv_rmhandlers.S

···
 BEGIN_FTR_SECTION
 	/* Set partition DABR */
 	/* Do this before re-enabling PMU to avoid P7 DABR corruption bug */
-	li	r5,3
+	lwz	r5,VCPU_DABRX(r4)
 	ld	r6,VCPU_DABR(r4)
 	mtspr	SPRN_DABRX,r5
 	mtspr	SPRN_DABR,r6
···
 	.long	0		/* 0x11c */
 	.long	0		/* 0x120 */
 	.long	.kvmppc_h_bulk_remove - hcall_real_table
+	.long	0		/* 0x128 */
+	.long	0		/* 0x12c */
+	.long	0		/* 0x130 */
+	.long	.kvmppc_h_set_xdabr - hcall_real_table
 hcall_real_table_end:
 
 ignore_hdec:
 	mr	r4,r9
 	b	fast_guest_return
 
+_GLOBAL(kvmppc_h_set_xdabr)
+	andi.	r0, r5, DABRX_USER | DABRX_KERNEL
+	beq	6f
+	li	r0, DABRX_USER | DABRX_KERNEL | DABRX_BTI
+	andc.	r0, r5, r0
+	beq	3f
+6:	li	r3, H_PARAMETER
+	blr
+
 _GLOBAL(kvmppc_h_set_dabr)
+	li	r5, DABRX_USER | DABRX_KERNEL
+3:
 BEGIN_FTR_SECTION
 	b	2f
 END_FTR_SECTION_IFSET(CPU_FTR_ARCH_207S)
 	std	r4,VCPU_DABR(r3)
+	stw	r5, VCPU_DABRX(r3)
+	mtspr	SPRN_DABRX, r5
 	/* Work around P7 bug where DABR can get corrupted on mtspr */
 1:	mtspr	SPRN_DABR,r4
 	mfspr	r5, SPRN_DABR
 	cmpd	r4, r5
 	bne	1b
 	isync
-2:	li	r3,0
+	li	r3,0
+	blr
+
+	/* Emulate H_SET_DABR/X on P8 for the sake of compat mode guests */
+2:	rlwimi	r5, r4, 5, DAWRX_DR | DAWRX_DW
+	rlwimi	r5, r4, 1, DAWRX_WT
+	clrrdi	r4, r4, 3
+	std	r4, VCPU_DAWR(r3)
+	std	r5, VCPU_DAWRX(r3)
+	mtspr	SPRN_DAWR, r4
+	mtspr	SPRN_DAWRX, r5
+	li	r3, 0
 	blr
 
 _GLOBAL(kvmppc_h_cede)