[PATCH 2/6] x86: hv: hv_init.c: Replace alloc_page() with kmem_cache_alloc()

[Maya Nakamura]

Switch from the function that allocates a single Linux guest page to a
different one to use a Hyper-V page because the guest page size and
hypervisor page size concepts are different, even though they happen to
be the same value on x86.

Signed-off-by: Maya Nakamura <m.maya.nakamura@xxxxxxxxx>
---
 arch/x86/hyperv/hv_init.c | 38 +++++++++++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 11 deletions(-)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index e4ba467a9fc6..5f946135aa18 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -31,6 +31,7 @@
 #include <linux/hyperv.h>
 #include <linux/slab.h>
 #include <linux/cpuhotplug.h>
+#include <asm/set_memory.h>
 
 #ifdef CONFIG_HYPERV_TSCPAGE
 
@@ -98,18 +99,20 @@ EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
 u32 hv_max_vp_index;
 EXPORT_SYMBOL_GPL(hv_max_vp_index);
 
+struct kmem_cache *cachep;
+EXPORT_SYMBOL_GPL(cachep);
+
 static int hv_cpu_init(unsigned int cpu)
 {
 	u64 msr_vp_index;
 	struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
 	void **input_arg;
-	struct page *pg;
 
 	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
-	pg = alloc_page(GFP_KERNEL);
-	if (unlikely(!pg))
+	*input_arg = kmem_cache_alloc(cachep, GFP_KERNEL);
+
+	if (unlikely(!*input_arg))
 		return -ENOMEM;
-	*input_arg = page_address(pg);
 
 	hv_get_vp_index(msr_vp_index);
 
@@ -122,14 +125,12 @@ static int hv_cpu_init(unsigned int cpu)
 		return 0;
 
 	if (!*hvp)
-		*hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
+		*hvp = kmem_cache_alloc(cachep, GFP_KERNEL);
 
 	if (*hvp) {
 		u64 val;
 
-		val = vmalloc_to_pfn(*hvp);
-		val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
-			HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
+		val = virt_to_phys(*hvp) | HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
 
 		wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
 	}
@@ -233,17 +234,22 @@ static int hv_cpu_die(unsigned int cpu)
 	unsigned long flags;
 	void **input_arg;
 	void *input_pg = NULL;
+	struct hv_vp_assist_page **hvp = &hv_vp_assist_page[cpu];
 
 	local_irq_save(flags);
 	input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
 	input_pg = *input_arg;
 	*input_arg = NULL;
 	local_irq_restore(flags);
-	free_page((unsigned long)input_pg);
+	kmem_cache_free(cachep, input_pg);
+	input_pg = NULL;
 
 	if (hv_vp_assist_page && hv_vp_assist_page[cpu])
 		wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
 
+	kmem_cache_free(cachep, *hvp);
+	*hvp = NULL;
+
 	if (hv_reenlightenment_cb == NULL)
 		return 0;
 
@@ -325,6 +331,11 @@ void __init hyperv_init(void)
 		goto free_vp_index;
 	}
 
+	cachep = kmem_cache_create("hyperv_pages", HV_HYP_PAGE_SIZE,
+				   HV_HYP_PAGE_SIZE, 0, NULL);
+	if (!cachep)
+		goto free_vp_assist_page;
+
 	cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
 				  hv_cpu_init, hv_cpu_die);
 	if (cpuhp < 0)
@@ -338,7 +349,10 @@ void __init hyperv_init(void)
 	guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
 	wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
 
-	hv_hypercall_pg  = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL_RX);
+	hv_hypercall_pg = kmem_cache_alloc(cachep, GFP_KERNEL);
+	if (hv_hypercall_pg)
+		set_memory_x((unsigned long)hv_hypercall_pg, 1);
+
 	if (hv_hypercall_pg == NULL) {
 		wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
 		goto remove_cpuhp_state;
@@ -346,7 +360,8 @@ void __init hyperv_init(void)
 
 	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 	hypercall_msr.enable = 1;
-	hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
+	hypercall_msr.guest_physical_address = virt_to_phys(hv_hypercall_pg) >>
+		HV_HYP_PAGE_SHIFT;
 	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
 
 	hv_apic_init();
@@ -416,6 +431,7 @@ void hyperv_cleanup(void)
 	 * let hypercall operations fail safely rather than
 	 * panic the kernel for using invalid hypercall page
 	 */
+	kmem_cache_free(cachep, hv_hypercall_pg);
 	hv_hypercall_pg = NULL;
 
 	/* Reset the hypercall page */
-- 
2.17.1