acpi: vmap pages in acpi_os_alloc_memory

Also, introduce a wrapper around vmap that maps a contiguous range for
boot allocations. Unfortunately, the new helper cannot be a static inline
because the dependencies are a mess. We would need to re-include
asm/page.h (was removed in aa4b9d1ee6 "include: don't use asm/page.h
from common headers") and it doesn't look to be enough anymore
because bits from asm/cpufeature.h is used in the definition of PAGE_NX.

Lastly, with the move to vmap(), it is now easier to find the size
of the mapping. So pass the whole area to init_boot_pages() rather than
just the first page.

Signed-off-by: Hongyan Xia <hongyxia@amazon.com>
Signed-off-by: Julien Grall <jgrall@amazon.com>
Signed-off-by: Elias El Yandouzi <eliasely@amazon.com>
Acked-by: Jan Beulich <jbeulich@suse.com>

xen/common/vmap.c

@@ -245,6 +245,11 @@ void *vmap(const mfn_t *mfn, unsigned int nr)
     return __vmap(mfn, 1, nr, 1, PAGE_HYPERVISOR, VMAP_DEFAULT);
 }
 
+void *vmap_contig(mfn_t mfn, unsigned int nr)
+{
+    return __vmap(&mfn, nr, 1, 1, PAGE_HYPERVISOR, VMAP_DEFAULT);
+}
+
 unsigned int vmap_size(const void *va)
 {
     unsigned int pages = vm_size(va, VMAP_DEFAULT);

xen/drivers/acpi/osl.c

@@ -221,7 +221,11 @@ void *__init acpi_os_alloc_memory(size_t sz)
 	void *ptr;
 
 	if (system_state == SYS_STATE_early_boot)
-		return mfn_to_virt(mfn_x(alloc_boot_pages(PFN_UP(sz), 1)));
+	{
+		mfn_t mfn = alloc_boot_pages(PFN_UP(sz), 1);
+
+		return vmap_contig(mfn, PFN_UP(sz));
+	}
 
 	ptr = xmalloc_bytes(sz);
 	ASSERT(!ptr || is_xmalloc_memory(ptr));
@@ -246,5 +250,11 @@ void __init acpi_os_free_memory(void *ptr)
 	if (is_xmalloc_memory(ptr))
 		xfree(ptr);
 	else if (ptr && system_state == SYS_STATE_early_boot)
-		init_boot_pages(__pa(ptr), __pa(ptr) + PAGE_SIZE);
+	{
+		paddr_t addr = mfn_to_maddr(vmap_to_mfn(ptr));
+		unsigned int nr = vmap_size(ptr);
+
+		vunmap(ptr);
+		init_boot_pages(addr, addr + nr * PAGE_SIZE);
+	}
 }

xen/include/xen/vmap.h

@@ -15,6 +15,7 @@ void vm_init_type(enum vmap_region type, void *start, void *end);
 void *__vmap(const mfn_t *mfn, unsigned int granularity, unsigned int nr,
              unsigned int align, unsigned int flags, enum vmap_region type);
 void *vmap(const mfn_t *mfn, unsigned int nr);
+void *vmap_contig(mfn_t mfn, unsigned int nr);
 void vunmap(const void *va);
 
 void *vmalloc(size_t size);