mm: properly implement page locking

kernel-src/include/kernel/iovec.h

@@ -66,10 +66,12 @@ size_t iovec_iterator_read_from_ringbuffer(iovec_iterator_t *iovec_iterator, rin
 // NOTE: the iovec can have userspace addresses. in this case, the copy can possibly fail with RINGBUFFER_USER_COPY_FAILED
 size_t iovec_iterator_peek_from_ringbuffer(iovec_iterator_t *iovec_iterator, ringbuffer_t *ringbuffer, size_t byte_count, uintmax_t ringbuffer_offset);
 
-// returns the physical address of the next page in the iovec_iterator, adding a reference count while at it
+// returns the physical address of the next page in the iovec_iterator, adding a reference count and locking it for DMA. 
+// The write bool controls whether the hint passed to mm_get_physical_address is a read or write (i.e. reading data from the page or 
+// writing data to the page)
 // sets the page_offset to the offset in the page, page_remaining to the remaining number of bytes in the page and page to the physical address of the page
 // if no more pages in iovec_iterator, returns success with page being set to NULL
 // fails with EFAULT if the page is not mapped
-int iovec_iterator_next_page(iovec_iterator_t *iovec_iterator, size_t *page_offset, size_t *page_remaining, void **page);
+int iovec_iterator_next_page(iovec_iterator_t *iovec_iterator, size_t *page_offset, size_t *page_remaining, void **page, bool write);
 
 #endif

kernel-src/include/kernel/mm.h

@@ -90,6 +90,8 @@ void mm_switch_context(mm_context_t *ctx);
 
 #define MM_GET_PHYSICAL_ADDRESS_FLAGS_HOLD 1
 #define MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK 2
+#define MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK_HINT_READ 4
+#define MM_GET_PHYSICAL_ADDRESS_FLAGS_LOCK_HINT_WRITE 8
 void *mm_get_physical_address(void *addr, int flags);
 void mm_apinit();
 void mm_init();

kernel-src/include/kernel/page.h

@@ -3,6 +3,7 @@
 
 #include <stddef.h>
 #include <stdint.h>
+#include <stdbool.h>
 
 #define MEMORY_SECTION_COUNT 3
 #define MEMORY_SECTION_1MB 0
@@ -44,11 +45,14 @@ page_t *mm_get_page(void *addr);
 void *mm_get_page_address(page_t *);
 void mm_hold_page(void *addr);
 void mm_release_page(void *addr);
+void mm_unlock_and_release_page(void *addr);
 void mm_force_free_page(void *address, size_t count);
 void *mm_alloc_pages(size_t size, int section);
 void mm_release_range(void *addr, size_t size);
 void mm_page_init();
 void mm_get_page_statistics(size_t *total_pages, size_t *free_pages);
+void mm_unlock_page(page_t *page);
+bool mm_is_page_locked(page_t *page);
 
 extern uintptr_t hhdm_base;
 

kernel-src/include/kernel/xhci.h

@@ -322,6 +322,7 @@ struct xhci_submission {
 	list_node_t list_node;
 	// Set whenever a submission is queued
 	bool valid;
+	bool unlock_pages;
 	struct xhci_ring *ring;
 
 	// The data associated with this submission