lcd/iommu: Allow unmapping over multiple pages

Signed-off-by: Vikram Narayanan <vikram186@gmail.com>

lcd-domains/arch/x86/include/asm/lcd_domains/liblcd.h

@@ -221,9 +221,9 @@ static inline int lcd_syscall_iommu_map_page(gpa_t gpa, unsigned int order, bool
 	return lcd_syscall_three_args(LCD_SYSCALL_IOMMU_MAP_PAGE, gpa_val(gpa), order, force);
 }
 
-static inline int lcd_syscall_iommu_unmap_page(gpa_t gpa)
+static inline int lcd_syscall_iommu_unmap_page(gpa_t gpa, unsigned int order)
 {
-	return lcd_syscall_one_arg(LCD_SYSCALL_IOMMU_UNMAP_PAGE, gpa_val(gpa));
+	return lcd_syscall_two_args(LCD_SYSCALL_IOMMU_UNMAP_PAGE, gpa_val(gpa), order);
 }
 
 static inline int lcd_syscall_create_sync_ep(cptr_t slot)

lcd-domains/include/lcd_domains/lcd_iommu.h

@@ -36,7 +36,7 @@ int lcd_iommu_map_memory(struct lcd *lcd);
  */
 int lcd_iommu_map_page(struct lcd *lcd, gpa_t gpa, unsigned int, bool force);
 
-int lcd_iommu_unmap_page(struct lcd *lcd, gpa_t gpa);
+int lcd_iommu_unmap_page(struct lcd *lcd, gpa_t gpa, unsigned int);
 
 /**
  * unmap the mappings from iommu. The logic is similar to mapping, except

lcd-domains/microkernel/iommu.c

@@ -94,30 +94,46 @@ int lcd_iommu_map_page(struct lcd *lcd, gpa_t gpa, unsigned int order,
 	return ret;
 }
 
-int lcd_iommu_unmap_page(struct lcd *lcd, gpa_t gpa)
+int lcd_iommu_unmap_page(struct lcd *lcd, gpa_t gpa, unsigned int order)
 {
 	hpa_t hpa;
 	int ret;
+	int i;
+	u64 gfn_start, gfn_end = 1 << order;
 
-	ret = lcd_arch_ept_gpa_to_hpa(lcd->lcd_arch, gpa, &hpa, true);
-
-	/* no mapping. Just return */
-	if (ret) {
-		LIBLCD_WARN("%s, spurious unmap to gpa:hpa %lx:%lx pair",
-			    __func__, gpa_val(gpa), hpa_val(hpa));
-		return 0;
-	}
+	gfn_start = gpa_to_gfn(gpa_val(gpa));
 
 	if (!lcd->domain)
 		return -EINVAL;
 
-	ret = iommu_iova_to_phys(lcd->domain, gpa_val(gpa));
+	for (i = 0; i < gfn_end; ++i) {
+		gpa_t ga = gfn_to_gpa(gfn_start + i);
 
-	if (ret) {
-		/* A valid mapping is present */
-		ret = iommu_unmap(lcd->domain, gpa_val(gpa), PAGE_SIZE);
-		/* bug if not a page */
-		BUG_ON(ret != PAGE_SIZE);
+		ret = lcd_arch_ept_gpa_to_hpa(lcd->lcd_arch, ga, &hpa, false);
+
+		/* no mapping. Just return */
+		/* TODO: it might be possible that the LCD has freed the memory
+		 * without freeing the iommu mapping. in that case, it is
+		 * messed up, but we can still go ahead and try to unmap it.
+		 * This is has to be handled in a more cleaner way.
+		 */
+		if (ret) {
+			LIBLCD_WARN("%s, spurious unmap to gpa:hpa %lx:%lx pair",
+				    __func__, gpa_val(ga), hpa_val(hpa));
+			continue;
+		}
+
+		ret = iommu_iova_to_phys(lcd->domain, gpa_val(ga));
+
+		printk("%s, unmapping gpa:hpa %lx:%lx pair\n", __func__,
+		       gpa_val(ga), hpa_val(hpa));
+
+		if (ret) {
+			/* A valid mapping is present */
+			ret = iommu_unmap(lcd->domain, gpa_val(ga), PAGE_SIZE);
+			/* bug if not a page */
+			BUG_ON(ret != PAGE_SIZE);
+		}
 	}
 	/* return success */
 	return 0;

lcd-domains/microkernel/run.c

@@ -323,10 +323,12 @@ static int handle_syscall_iommu_unmap_page(struct lcd *lcd)
 {
 	int ret;
 	gpa_t gpa;
+	int order;
 
 	gpa = __gpa(lcd_arch_get_syscall_arg0(lcd->lcd_arch));
+	order = lcd_arch_get_syscall_arg1(lcd->lcd_arch);
 
-	ret = lcd_iommu_unmap_page(lcd, gpa);
+	ret = lcd_iommu_unmap_page(lcd, gpa, order);
 	return ret;
 }