add interface providing the free list to the hypervisor (hermit-os#101)

Add an interface for sharing the free list with the hypervisor. This can be used to accelerate the cold migration of guests.

Author: Simon Pickartz

arch/aarch64/mm/memory.c

@@ -64,6 +64,11 @@ atomic_int64_t total_pages = ATOMIC_INIT(0);
 atomic_int64_t total_allocated_pages = ATOMIC_INIT(0);
 atomic_int64_t total_available_pages = ATOMIC_INIT(0);
 
+free_list_t *get_free_list(void)
+{
+	return free_start;
+}
+
 size_t get_pages(size_t npages)
 {
 	size_t i, ret = 0;

arch/x86_64/mm/memory.c

@@ -134,6 +134,11 @@ static size_t __get_pages(size_t npages, size_t align)
 	return ret;
 }
 
+free_list_t *get_free_list(void)
+{
+	return free_start;
+}
+
 size_t get_pages(size_t npages)
 {
 	return __get_pages(npages, PAGE_SIZE);

caves

@@ -58,7 +58,7 @@
 
 #include "uhyve-net.h"
 
-#define UHYVE_IRQ	11
+#define UHYVE_IRQ_NET	11
 
 static int8_t uhyve_net_init_ok = 0;
 static struct netif* mynetif = NULL;
@@ -257,8 +257,8 @@ err_t uhyve_netif_init (struct netif* netif)
 	LWIP_DEBUGF(NETIF_DEBUG, ("\n"));
 	uhyve_netif->ethaddr = (struct eth_addr *)netif->hwaddr;
 
-	LOG_INFO("uhye_netif uses irq %d\n", UHYVE_IRQ);
-	irq_install_handler(32+UHYVE_IRQ, uhyve_irqhandler);
+	LOG_INFO("uhye_netif uses irq %d\n", UHYVE_IRQ_NET);
+	irq_install_handler(32+UHYVE_IRQ_NET, uhyve_irqhandler);
 
 	/*
 	 * Initialize the snmp variables and counters inside the struct netif.

drivers/net/uhyve-net.c

@@ -36,12 +36,17 @@
 #ifndef __MEMORY_H__
 #define __MEMORY_H__
 
+typedef struct free_list free_list_t;
+
 /** @brief Initialize the memory subsystem */
 int memory_init(void);
 
 /** @brief Request physical page frames */
 size_t get_pages(size_t npages);
 
+/** @brief Returns a pointer to the free_list */
+free_list_t *get_free_list(void);
+
 /** @brief Get a single page
  *
  * Convenience function: uses get_pages(1);

include/hermit/memory.h

@@ -74,6 +74,8 @@ extern size_t image_size;
 #define UHYVE_PORT_NETREAD		0x680
 #define UHYVE_PORT_NETSTAT		0x700
 
+#define UHYVE_PORT_FREELIST 		0x720
+
 /* Ports and data structures for uhyve command line arguments and envp
  * forwarding */
 #define UHYVE_PORT_CMDSIZE		0x740

include/hermit/stddef.h

@@ -37,6 +37,7 @@
 #define __VMA_H__
 
 #include <hermit/stddef.h>
+#include <hermit/memory.h>
 #include <asm/page.h>
 
 #ifdef __cplusplus

include/hermit/vma.h

@@ -32,7 +32,10 @@
 #include <hermit/spinlock.h>
 #include <hermit/errno.h>
 #include <hermit/logging.h>
+#include <asm/io.h>
+#include <asm/irq.h>
 
+#define UHYVE_IRQ_FREELIST 12
 /*
  * Note that linker symbols are not variables, they have no memory allocated for
  * maintaining a value, rather their address is their value.
@@ -49,6 +52,13 @@ static vma_t vma_boot = { VMA_MIN, VMA_MIN, VMA_HEAP };
 static vma_t* vma_list = &vma_boot;
 spinlock_irqsave_t hermit_mm_lock = SPINLOCK_IRQSAVE_INIT;
 
+typedef struct free_list free_list_t;
+
+static void uhyve_irq_freelist_handler(struct state* s)
+{
+	outportl(UHYVE_PORT_FREELIST, (unsigned)virt_to_phys((size_t)get_free_list()));
+}
+
 int vma_init(void)
 {
 	int ret;
@@ -68,7 +78,11 @@ int vma_init(void)
 	ret = vma_add(HEAP_START, HEAP_START+HEAP_SIZE, VMA_NO_ACCESS);
 	if (BUILTIN_EXPECT(ret, 0))
 		goto out;
-	LOG_INFO("Reserve space for the heap: 0x%llx - 0x%llx\n", HEAP_START, HEAP_START+HEAP_SIZE-1); 
+	LOG_INFO("Reserve space for the heap: 0x%llx - 0x%llx\n", HEAP_START, HEAP_START+HEAP_SIZE-1);
+
+	// install IRQ handler for the migration interface
+	LOG_INFO("freelist channel uses irq %d\n", UHYVE_IRQ_FREELIST);
+	irq_install_handler(32+UHYVE_IRQ_FREELIST, uhyve_irq_freelist_handler);
 
 	// we might move the architecture specific VMA regions to a
 	// seperate function vma_arch_init()