Merge tag 'x86-urgent-2021-11-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 fixes from Thomas Gleixner:

 - Move the command line preparation and the early command line parsing
   earlier so that the command line parameters which affect
   early_reserve_memory(), e.g. efi=nosftreserve, are taken into
   account. This was broken when the invocation of
   early_reserve_memory() was moved recently.

 - Use an atomic type for the SGX page accounting, which is read and
   written locklessly, to plug various race conditions related to it.

* tag 'x86-urgent-2021-11-21' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/sgx: Fix free page accounting
  x86/boot: Pull up cmdline preparation and early param parsing

2 files changed, 45 insertions, 33 deletions

diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
index 63d3de02bbcc..8471a8b9b48e 100644
--- a/arch/x86/kernel/cpu/sgx/main.c
+++ b/arch/x86/kernel/cpu/sgx/main.c
@@ -28,8 +28,7 @@ static DECLARE_WAIT_QUEUE_HEAD(ksgxd_waitq);
 static LIST_HEAD(sgx_active_page_list);
 static DEFINE_SPINLOCK(sgx_reclaimer_lock);
 
-/* The free page list lock protected variables prepend the lock. */
-static unsigned long sgx_nr_free_pages;
+static atomic_long_t sgx_nr_free_pages = ATOMIC_LONG_INIT(0);
 
 /* Nodes with one or more EPC sections. */
 static nodemask_t sgx_numa_mask;
@@ -403,14 +402,15 @@ skip:
 
 		spin_lock(&node->lock);
 		list_add_tail(&epc_page->list, &node->free_page_list);
-		sgx_nr_free_pages++;
 		spin_unlock(&node->lock);
+		atomic_long_inc(&sgx_nr_free_pages);
 	}
 }
 
 static bool sgx_should_reclaim(unsigned long watermark)
 {
-	return sgx_nr_free_pages < watermark && !list_empty(&sgx_active_page_list);
+	return atomic_long_read(&sgx_nr_free_pages) < watermark &&
+	       !list_empty(&sgx_active_page_list);
 }
 
 static int ksgxd(void *p)
@@ -471,9 +471,9 @@ static struct sgx_epc_page *__sgx_alloc_epc_page_from_node(int nid)
 
 	page = list_first_entry(&node->free_page_list, struct sgx_epc_page, list);
 	list_del_init(&page->list);
-	sgx_nr_free_pages--;
 
 	spin_unlock(&node->lock);
+	atomic_long_dec(&sgx_nr_free_pages);
 
 	return page;
 }
@@ -625,9 +625,9 @@ void sgx_free_epc_page(struct sgx_epc_page *page)
 	spin_lock(&node->lock);
 
 	list_add_tail(&page->list, &node->free_page_list);
-	sgx_nr_free_pages++;
 
 	spin_unlock(&node->lock);
+	atomic_long_inc(&sgx_nr_free_pages);
 }
 
 static bool __init sgx_setup_epc_section(u64 phys_addr, u64 size,
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 49b596db5631..c410be738ae7 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -742,6 +742,28 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
 	return 0;
 }
 
+static char *prepare_command_line(void)
+{
+#ifdef CONFIG_CMDLINE_BOOL
+#ifdef CONFIG_CMDLINE_OVERRIDE
+	strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+#else
+	if (builtin_cmdline[0]) {
+		/* append boot loader cmdline to builtin */
+		strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
+		strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
+		strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
+	}
+#endif
+#endif
+
+	strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
+
+	parse_early_param();
+
+	return command_line;
+}
+
 /*
  * Determine if we were loaded by an EFI loader.  If so, then we have also been
  * passed the efi memmap, systab, etc., so we should use these data structures
@@ -831,6 +853,23 @@ void __init setup_arch(char **cmdline_p)
 	x86_init.oem.arch_setup();
 
 	/*
+	 * x86_configure_nx() is called before parse_early_param() (called by
+	 * prepare_command_line()) to detect whether hardware doesn't support
+	 * NX (so that the early EHCI debug console setup can safely call
+	 * set_fixmap()). It may then be called again from within noexec_setup()
+	 * during parsing early parameters to honor the respective command line
+	 * option.
+	 */
+	x86_configure_nx();
+
+	/*
+	 * This parses early params and it needs to run before
+	 * early_reserve_memory() because latter relies on such settings
+	 * supplied as early params.
+	 */
+	*cmdline_p = prepare_command_line();
+
+	/*
 	 * Do some memory reservations *before* memory is added to memblock, so
 	 * memblock allocations won't overwrite it.
 	 *
@@ -863,33 +902,6 @@ void __init setup_arch(char **cmdline_p)
 	bss_resource.start = __pa_symbol(__bss_start);
 	bss_resource.end = __pa_symbol(__bss_stop)-1;
 
-#ifdef CONFIG_CMDLINE_BOOL
-#ifdef CONFIG_CMDLINE_OVERRIDE
-	strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
-#else
-	if (builtin_cmdline[0]) {
-		/* append boot loader cmdline to builtin */
-		strlcat(builtin_cmdline, " ", COMMAND_LINE_SIZE);
-		strlcat(builtin_cmdline, boot_command_line, COMMAND_LINE_SIZE);
-		strlcpy(boot_command_line, builtin_cmdline, COMMAND_LINE_SIZE);
-	}
-#endif
-#endif
-
-	strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
-	*cmdline_p = command_line;
-
-	/*
-	 * x86_configure_nx() is called before parse_early_param() to detect
-	 * whether hardware doesn't support NX (so that the early EHCI debug
-	 * console setup can safely call set_fixmap()). It may then be called
-	 * again from within noexec_setup() during parsing early parameters
-	 * to honor the respective command line option.
-	 */
-	x86_configure_nx();
-
-	parse_early_param();
-
 #ifdef CONFIG_MEMORY_HOTPLUG
 	/*
 	 * Memory used by the kernel cannot be hot-removed because Linux