xen/x86: Add interface for querying amount of host memory

A driver (or some other entity in the kernel) may need to know
amount of memory available on the host. Provide the interface (for
a privileged domain() to obtain this information.

Orabug: 26526923

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

diff --git a/arch/x86/include/asm/xen/hypervisor.h b/arch/x86/include/asm/xen/hypervisor.h
index 0c47f1afb3a00bd2e66843926223fc87fde6b228..aa1e2f086a80397645f36320241c5be39371a7b1 100644 (file)
--- a/arch/x86/include/asm/xen/hypervisor.h
+++ b/arch/x86/include/asm/xen/hypervisor.h
@@ -45,6 +45,7 @@ static inline uint32_t xen_cpuid_base(void)
 
 #ifdef CONFIG_XEN
 extern bool xen_hvm_need_lapic(void);
+extern int xen_get_host_pages(unsigned long *num_pages);
 
 static inline bool xen_x2apic_para_available(void)
 {
@@ -55,6 +56,10 @@ static inline bool xen_x2apic_para_available(void)
 {
        return (xen_cpuid_base() != 0);
 }
+static inline int xen_get_host_pages(unsigned long *num_pages)
+{
+       return -EOPNOTSUPP;
+}
 #endif
 
 void xen_set_iopl_mask(unsigned mask);

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 96062f109fbb413bd4389181290e69d3eea80c55..6aa28967d7efa561d3e87f369b409e75a29731c7 100644 (file)
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -1981,3 +1981,39 @@ void xen_arch_unregister_cpu(int num)
 }
 EXPORT_SYMBOL(xen_arch_unregister_cpu);
 #endif
+
+/* UEK-specific routine */
+int xen_get_host_pages(unsigned long *num_pages)
+{
+       struct xen_memory_map memmap;
+       struct e820entry *e820map;
+       unsigned long sz = 0;
+       int i, rc;
+
+       if (!xen_domain())
+               return -EOPNOTSUPP;
+       if (!xen_initial_domain())
+               return -EPERM;
+
+       memmap.nr_entries = E820_X_MAX;
+       e820map = kmalloc(sizeof(*e820map) * memmap.nr_entries, GFP_KERNEL);
+       if (e820map == NULL)
+               return -ENOMEM;
+       set_xen_guest_handle(memmap.buffer, e820map);
+
+       rc = HYPERVISOR_memory_op(XENMEM_machine_memory_map, &memmap);
+       if (rc)
+               goto out;
+
+       for (i = 0; i < memmap.nr_entries; i++) {
+               if (e820map[i].type == E820_RAM)
+                       sz += e820map[i].size;
+       }
+
+       *num_pages = (sz >> PAGE_SHIFT);
+
+ out:
+       kfree(e820map);
+       return rc;
+}
+EXPORT_SYMBOL(xen_get_host_pages);