acpi, apei, ghes: Factor out ioremap virtual memory for IRQ and NMI context.

GHES currently maps two pages with atomic_ioremap.  From now
on, NMI is architectural depended so there is no need to allocate
an NMI page for platforms without NMI support.

To make it possible to not use a second page, swap the existing
page order so that the IRQ context page is first, and the optional
NMI context page is second.  Then, use HAVE_ACPI_APEI_NMI to decide
how many pages are to be allocated.
Signed-off-by: Tomasz Nowicki <tomasz.nowicki@linaro.org>
Acked-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Tony Luck <tony.luck@intel.com>

arch/x86/kernel/acpi/apei.c

@@ -15,6 +15,7 @@
 #include <acpi/apei.h>
 
 #include <asm/mce.h>
+#include <asm/tlbflush.h>
 
 int arch_apei_enable_cmcff(struct acpi_hest_header *hest_hdr, void *data)
 {
@@ -54,3 +55,8 @@ void arch_apei_report_mem_error(int sev, struct cper_sec_mem_err *mem_err)
 	apei_mce_report_mem_error(sev, mem_err);
 #endif
 }
+
+void arch_apei_flush_tlb_one(unsigned long addr)
+{
+	__flush_tlb_one(addr);
+}

drivers/acpi/apei/ghes.c

@@ -105,12 +105,16 @@ static DEFINE_MUTEX(ghes_list_mutex);
  */
 
 /*
- * Two virtual pages are used, one for NMI context, the other for
- * IRQ/PROCESS context
+ * Two virtual pages are used, one for IRQ/PROCESS context, the other for
+ * NMI context (optionally).
  */
+#ifdef CONFIG_HAVE_ACPI_APEI_NMI
 #define GHES_IOREMAP_PAGES           2
-#define GHES_IOREMAP_NMI_PAGE(base)	(base)
-#define GHES_IOREMAP_IRQ_PAGE(base)	((base) + PAGE_SIZE)
+#else
+#define GHES_IOREMAP_PAGES           1
+#endif
+#define GHES_IOREMAP_IRQ_PAGE(base)	(base)
+#define GHES_IOREMAP_NMI_PAGE(base)	((base) + PAGE_SIZE)
 
 /* virtual memory area for atomic ioremap */
 static struct vm_struct *ghes_ioremap_area;
@@ -173,7 +177,7 @@ static void ghes_iounmap_nmi(void __iomem *vaddr_ptr)
 
 	BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_NMI_PAGE(base));
 	unmap_kernel_range_noflush(vaddr, PAGE_SIZE);
-	__flush_tlb_one(vaddr);
+	arch_apei_flush_tlb_one(vaddr);
 }
 
 static void ghes_iounmap_irq(void __iomem *vaddr_ptr)
@@ -183,7 +187,7 @@ static void ghes_iounmap_irq(void __iomem *vaddr_ptr)
 
 	BUG_ON(vaddr != (unsigned long)GHES_IOREMAP_IRQ_PAGE(base));
 	unmap_kernel_range_noflush(vaddr, PAGE_SIZE);
-	__flush_tlb_one(vaddr);
+	arch_apei_flush_tlb_one(vaddr);
 }
 
 static int ghes_estatus_pool_init(void)

include/acpi/apei.h

@@ -44,6 +44,7 @@ int erst_clear(u64 record_id);
 
 int arch_apei_enable_cmcff(struct acpi_hest_header *hest_hdr, void *data);
 void arch_apei_report_mem_error(int sev, struct cper_sec_mem_err *mem_err);
+void arch_apei_flush_tlb_one(unsigned long addr);
 
 #endif
 #endif