powerpc: Fix compile issue with force DAWR

If you compile with KVM but without CONFIG_HAVE_HW_BREAKPOINT you fail
at linking with:
  arch/powerpc/kvm/book3s_hv_rmhandlers.o:(.text+0x708): undefined reference to `dawr_force_enable'

This was caused by commit c1fe190 ("powerpc: Add force enable of
DAWR on P9 option").

This moves a bunch of code around to fix this. It moves a lot of the
DAWR code in a new file and creates a new CONFIG_PPC_DAWR to enable
compiling it.

Fixes: c1fe190 ("powerpc: Add force enable of DAWR on P9 option")
Signed-off-by: Michael Neuling <mikey@neuling.org>
[mpe: Minor formatting in set_dawr()]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/Kconfig

@@ -236,6 +236,7 @@ config PPC
 	select OLD_SIGSUSPEND
 	select PCI_DOMAINS			if PCI
 	select PCI_SYSCALL			if PCI
+	select PPC_DAWR				if PPC64
 	select RTC_LIB
 	select SPARSE_IRQ
 	select SYSCTL_EXCEPTION_TRACE
@@ -372,6 +373,9 @@ config PPC_ADV_DEBUG_DAC_RANGE
 	depends on PPC_ADV_DEBUG_REGS && 44x
 	default y
 
+config PPC_DAWR
+	bool
+
 config ZONE_DMA
 	bool
 	default y if PPC_BOOK3E_64

arch/powerpc/include/asm/hw_breakpoint.h

@@ -90,18 +90,25 @@ static inline void hw_breakpoint_disable(void)
 extern void thread_change_pc(struct task_struct *tsk, struct pt_regs *regs);
 int hw_breakpoint_handler(struct die_args *args);
 
-extern int set_dawr(struct arch_hw_breakpoint *brk);
+#else	/* CONFIG_HAVE_HW_BREAKPOINT */
+static inline void hw_breakpoint_disable(void) { }
+static inline void thread_change_pc(struct task_struct *tsk,
+					struct pt_regs *regs) { }
+
+#endif	/* CONFIG_HAVE_HW_BREAKPOINT */
+
+
+#ifdef CONFIG_PPC_DAWR
 extern bool dawr_force_enable;
 static inline bool dawr_enabled(void)
 {
 	return dawr_force_enable;
 }
-
-#else	/* CONFIG_HAVE_HW_BREAKPOINT */
-static inline void hw_breakpoint_disable(void) { }
-static inline void thread_change_pc(struct task_struct *tsk,
-					struct pt_regs *regs) { }
+int set_dawr(struct arch_hw_breakpoint *brk);
+#else
 static inline bool dawr_enabled(void) { return false; }
-#endif	/* CONFIG_HAVE_HW_BREAKPOINT */
+static inline int set_dawr(struct arch_hw_breakpoint *brk) { return -1; }
+#endif
+
 #endif	/* __KERNEL__ */
 #endif	/* _PPC_BOOK3S_64_HW_BREAKPOINT_H */

arch/powerpc/kernel/Makefile

@@ -56,6 +56,7 @@ obj-$(CONFIG_PPC64)		+= setup_64.o sys_ppc32.o \
 obj-$(CONFIG_VDSO32)		+= vdso32/
 obj-$(CONFIG_PPC_WATCHDOG)	+= watchdog.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
+obj-$(CONFIG_PPC_DAWR)		+= dawr.o
 obj-$(CONFIG_PPC_BOOK3S_64)	+= cpu_setup_ppc970.o cpu_setup_pa6t.o
 obj-$(CONFIG_PPC_BOOK3S_64)	+= cpu_setup_power.o
 obj-$(CONFIG_PPC_BOOK3S_64)	+= mce.o mce_power.o

arch/powerpc/kernel/dawr.c

@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * DAWR infrastructure
+ *
+ * Copyright 2019, Michael Neuling, IBM Corporation.
+ */
+
+#include <linux/types.h>
+#include <linux/export.h>
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <asm/debugfs.h>
+#include <asm/machdep.h>
+#include <asm/hvcall.h>
+
+bool dawr_force_enable;
+EXPORT_SYMBOL_GPL(dawr_force_enable);
+
+int set_dawr(struct arch_hw_breakpoint *brk)
+{
+	unsigned long dawr, dawrx, mrd;
+
+	dawr = brk->address;
+
+	dawrx  = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE))
+		<< (63 - 58);
+	dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) << (63 - 59);
+	dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) >> 3;
+	/*
+	 * DAWR length is stored in field MDR bits 48:53.  Matches range in
+	 * doublewords (64 bits) baised by -1 eg. 0b000000=1DW and
+	 * 0b111111=64DW.
+	 * brk->len is in bytes.
+	 * This aligns up to double word size, shifts and does the bias.
+	 */
+	mrd = ((brk->len + 7) >> 3) - 1;
+	dawrx |= (mrd & 0x3f) << (63 - 53);
+
+	if (ppc_md.set_dawr)
+		return ppc_md.set_dawr(dawr, dawrx);
+
+	mtspr(SPRN_DAWR, dawr);
+	mtspr(SPRN_DAWRX, dawrx);
+
+	return 0;
+}
+
+static void set_dawr_cb(void *info)
+{
+	set_dawr(info);
+}
+
+static ssize_t dawr_write_file_bool(struct file *file,
+				    const char __user *user_buf,
+				    size_t count, loff_t *ppos)
+{
+	struct arch_hw_breakpoint null_brk = {0, 0, 0};
+	size_t rc;
+
+	/* Send error to user if they hypervisor won't allow us to write DAWR */
+	if (!dawr_force_enable &&
+	    firmware_has_feature(FW_FEATURE_LPAR) &&
+	    set_dawr(&null_brk) != H_SUCCESS)
+		return -ENODEV;
+
+	rc = debugfs_write_file_bool(file, user_buf, count, ppos);
+	if (rc)
+		return rc;
+
+	/* If we are clearing, make sure all CPUs have the DAWR cleared */
+	if (!dawr_force_enable)
+		smp_call_function(set_dawr_cb, &null_brk, 0);
+
+	return rc;
+}
+
+static const struct file_operations dawr_enable_fops = {
+	.read =		debugfs_read_file_bool,
+	.write =	dawr_write_file_bool,
+	.open =		simple_open,
+	.llseek =	default_llseek,
+};
+
+static int __init dawr_force_setup(void)
+{
+	if (cpu_has_feature(CPU_FTR_DAWR)) {
+		/* Don't setup sysfs file for user control on P8 */
+		dawr_force_enable = true;
+		return 0;
+	}
+
+	if (PVR_VER(mfspr(SPRN_PVR)) == PVR_POWER9) {
+		/* Turn DAWR off by default, but allow admin to turn it on */
+		debugfs_create_file_unsafe("dawr_enable_dangerous", 0600,
+					   powerpc_debugfs_root,
+					   &dawr_force_enable,
+					   &dawr_enable_fops);
+	}
+	return 0;
+}
+arch_initcall(dawr_force_setup);

arch/powerpc/kernel/hw_breakpoint.c

@@ -380,64 +380,3 @@ void hw_breakpoint_pmu_read(struct perf_event *bp)
 {
 	/* TODO */
 }
-
-bool dawr_force_enable;
-EXPORT_SYMBOL_GPL(dawr_force_enable);
-
-static void set_dawr_cb(void *info)
-{
-	set_dawr(info);
-}
-
-static ssize_t dawr_write_file_bool(struct file *file,
-				    const char __user *user_buf,
-				    size_t count, loff_t *ppos)
-{
-	struct arch_hw_breakpoint null_brk = {0, 0, 0};
-	size_t rc;
-
-	/* Send error to user if they hypervisor won't allow us to write DAWR */
-	if ((!dawr_force_enable) &&
-	    (firmware_has_feature(FW_FEATURE_LPAR)) &&
-	    (set_dawr(&null_brk) != H_SUCCESS))
-		return -1;
-
-	rc = debugfs_write_file_bool(file, user_buf, count, ppos);
-	if (rc)
-		return rc;
-
-	/* If we are clearing, make sure all CPUs have the DAWR cleared */
-	if (!dawr_force_enable)
-		smp_call_function(set_dawr_cb, &null_brk, 0);
-
-	return rc;
-}
-
-static const struct file_operations dawr_enable_fops = {
-	.read =		debugfs_read_file_bool,
-	.write =	dawr_write_file_bool,
-	.open =		simple_open,
-	.llseek =	default_llseek,
-};
-
-static int __init dawr_force_setup(void)
-{
-	dawr_force_enable = false;
-
-	if (cpu_has_feature(CPU_FTR_DAWR)) {
-		/* Don't setup sysfs file for user control on P8 */
-		dawr_force_enable = true;
-		return 0;
-	}
-
-	if (PVR_VER(mfspr(SPRN_PVR)) == PVR_POWER9) {
-		/* Turn DAWR off by default, but allow admin to turn it on */
-		dawr_force_enable = false;
-		debugfs_create_file_unsafe("dawr_enable_dangerous", 0600,
-					   powerpc_debugfs_root,
-					   &dawr_force_enable,
-					   &dawr_enable_fops);
-	}
-	return 0;
-}
-arch_initcall(dawr_force_setup);

arch/powerpc/kernel/process.c

@@ -797,34 +797,6 @@ static inline int set_dabr(struct arch_hw_breakpoint *brk)
 	return __set_dabr(dabr, dabrx);
 }
 
-int set_dawr(struct arch_hw_breakpoint *brk)
-{
-	unsigned long dawr, dawrx, mrd;
-
-	dawr = brk->address;
-
-	dawrx  = (brk->type & (HW_BRK_TYPE_READ | HW_BRK_TYPE_WRITE)) \
-		                   << (63 - 58); //* read/write bits */
-	dawrx |= ((brk->type & (HW_BRK_TYPE_TRANSLATE)) >> 2) \
-		                   << (63 - 59); //* translate */
-	dawrx |= (brk->type & (HW_BRK_TYPE_PRIV_ALL)) \
-		                   >> 3; //* PRIM bits */
-	/* dawr length is stored in field MDR bits 48:53.  Matches range in
-	   doublewords (64 bits) baised by -1 eg. 0b000000=1DW and
-	   0b111111=64DW.
-	   brk->len is in bytes.
-	   This aligns up to double word size, shifts and does the bias.
-	*/
-	mrd = ((brk->len + 7) >> 3) - 1;
-	dawrx |= (mrd & 0x3f) << (63 - 53);
-
-	if (ppc_md.set_dawr)
-		return ppc_md.set_dawr(dawr, dawrx);
-	mtspr(SPRN_DAWR, dawr);
-	mtspr(SPRN_DAWRX, dawrx);
-	return 0;
-}
-
 void __set_breakpoint(struct arch_hw_breakpoint *brk)
 {
 	memcpy(this_cpu_ptr(&current_brk), brk, sizeof(*brk));

arch/powerpc/kvm/Kconfig

@@ -38,6 +38,7 @@ config KVM_BOOK3S_32_HANDLER
 config KVM_BOOK3S_64_HANDLER
 	bool
 	select KVM_BOOK3S_HANDLER
+	select PPC_DAWR_FORCE_ENABLE
 
 config KVM_BOOK3S_PR_POSSIBLE
 	bool