Drivers: hv: Make portions of Hyper-V init code be arch neutral

The code to allocate and initialize the hv_vp_index array is
architecture neutral. Similarly, the code to allocate and
populate the hypercall input and output arg pages is architecture
neutral.  Move both sets of code out from arch/x86 and into
utility functions in drivers/hv/hv_common.c that can be shared
by Hyper-V initialization on ARM64.

No functional changes. However, the allocation of the hypercall
input and output arg pages is done differently so that the
size is always the Hyper-V page size, even if not the same as
the guest page size (such as with ARM64's 64K page size).

Signed-off-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1626287687-2045-2-git-send-email-mikelley@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

1 files changed, 138 insertions, 0 deletions

diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
index 7f42da98d377..e836002bc0ce 100644
--- a/drivers/hv/hv_common.c
+++ b/drivers/hv/hv_common.c
@@ -15,9 +15,147 @@
 #include <linux/types.h>
 #include <linux/export.h>
 #include <linux/bitfield.h>
+#include <linux/cpumask.h>
+#include <linux/slab.h>
 #include <asm/hyperv-tlfs.h>
 #include <asm/mshyperv.h>
 
+/*
+ * hv_root_partition and ms_hyperv are defined here with other Hyper-V
+ * specific globals so they are shared across all architectures and are
+ * built only when CONFIG_HYPERV is defined.  But on x86,
+ * ms_hyperv_init_platform() is built even when CONFIG_HYPERV is not
+ * defined, and it uses these two variables.  So mark them as __weak
+ * here, allowing for an overriding definition in the module containing
+ * ms_hyperv_init_platform().
+ */
+bool __weak hv_root_partition;
+EXPORT_SYMBOL_GPL(hv_root_partition);
+
+struct ms_hyperv_info __weak ms_hyperv;
+EXPORT_SYMBOL_GPL(ms_hyperv);
+
+u32 *hv_vp_index;
+EXPORT_SYMBOL_GPL(hv_vp_index);
+
+u32 hv_max_vp_index;
+EXPORT_SYMBOL_GPL(hv_max_vp_index);
+
+void  __percpu **hyperv_pcpu_input_arg;
+EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
+
+void  __percpu **hyperv_pcpu_output_arg;
+EXPORT_SYMBOL_GPL(hyperv_pcpu_output_arg);
+
+/*
+ * Hyper-V specific initialization and shutdown code that is
+ * common across all architectures.  Called from architecture
+ * specific initialization functions.
+ */
+
+void __init hv_common_free(void)
+{
+	kfree(hv_vp_index);
+	hv_vp_index = NULL;
+
+	free_percpu(hyperv_pcpu_output_arg);
+	hyperv_pcpu_output_arg = NULL;
+
+	free_percpu(hyperv_pcpu_input_arg);
+	hyperv_pcpu_input_arg = NULL;
+}
+
+int __init hv_common_init(void)
+{
+	int i;
+
+	/*
+	 * Allocate the per-CPU state for the hypercall input arg.
+	 * If this allocation fails, we will not be able to setup
+	 * (per-CPU) hypercall input page and thus this failure is
+	 * fatal on Hyper-V.
+	 */
+	hyperv_pcpu_input_arg = alloc_percpu(void  *);
+	BUG_ON(!hyperv_pcpu_input_arg);
+
+	/* Allocate the per-CPU state for output arg for root */
+	if (hv_root_partition) {
+		hyperv_pcpu_output_arg = alloc_percpu(void *);
+		BUG_ON(!hyperv_pcpu_output_arg);
+	}
+
+	hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
+				    GFP_KERNEL);
+	if (!hv_vp_index) {
+		hv_common_free();
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < num_possible_cpus(); i++)
+		hv_vp_index[i] = VP_INVAL;
+
+	return 0;
+}
+
+/*
+ * Hyper-V specific initialization and die code for
+ * individual CPUs that is common across all architectures.
+ * Called by the CPU hotplug mechanism.
+ */
+
+int hv_common_cpu_init(unsigned int cpu)
+{
+	void **inputarg, **outputarg;
+	u64 msr_vp_index;
+	gfp_t flags;
+	int pgcount = hv_root_partition ? 2 : 1;
+
+	/* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
+	flags = irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL;
+
+	inputarg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	*inputarg = kmalloc(pgcount * HV_HYP_PAGE_SIZE, flags);
+	if (!(*inputarg))
+		return -ENOMEM;
+
+	if (hv_root_partition) {
+		outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
+		*outputarg = (char *)(*inputarg) + HV_HYP_PAGE_SIZE;
+	}
+
+	msr_vp_index = hv_get_register(HV_REGISTER_VP_INDEX);
+
+	hv_vp_index[cpu] = msr_vp_index;
+
+	if (msr_vp_index > hv_max_vp_index)
+		hv_max_vp_index = msr_vp_index;
+
+	return 0;
+}
+
+int hv_common_cpu_die(unsigned int cpu)
+{
+	unsigned long flags;
+	void **inputarg, **outputarg;
+	void *mem;
+
+	local_irq_save(flags);
+
+	inputarg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
+	mem = *inputarg;
+	*inputarg = NULL;
+
+	if (hv_root_partition) {
+		outputarg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
+		*outputarg = NULL;
+	}
+
+	local_irq_restore(flags);
+
+	kfree(mem);
+
+	return 0;
+}
 
 /* Bit mask of the extended capability to query: see HV_EXT_CAPABILITY_xxx */
 bool hv_query_ext_cap(u64 cap_query)