[RFC PATCH v7 05/13] irqchip/gic-v3-its: Allocate shared tables using CoCo shared memory allocator

["Aneesh Kumar K.V (Arm)" <aneesh.kumar@kernel.org>]

ITS command queues and tables are shared with the host in a
confidential-computing guest. The ITS allocator currently assumes that
the guest PAGE_SIZE is sufficient for both allocation alignment and
private/shared state changes.

Route ITS page allocations through alloc_cc_shared_pages_node(). Keep
the tracked table size based on the ITS-requested order. On release,
reconstruct the common allocation metadata from the original ITS order
and the architecture granule size so the same transitioned range and
buddy order are used.

Signed-off-by: Aneesh Kumar K.V (Arm) <aneesh.kumar@kernel.org>
---
 drivers/irqchip/irq-gic-v3-its.c | 40 ++++++++++++--------------------
 1 file changed, 15 insertions(+), 25 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index ac5507acb1a0..4814161df02e 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -8,6 +8,7 @@
 #include <linux/acpi_iort.h>
 #include <linux/bitfield.h>
 #include <linux/bitmap.h>
+#include <linux/cc_shared.h>
 #include <linux/cpu.h>
 #include <linux/crash_dump.h>
 #include <linux/delay.h>
@@ -19,7 +20,6 @@
 #include <linux/irqdomain.h>
 #include <linux/list.h>
 #include <linux/log2.h>
-#include <linux/mem_encrypt.h>
 #include <linux/memblock.h>
 #include <linux/mm.h>
 #include <linux/msi.h>
@@ -29,7 +29,6 @@
 #include <linux/of_pci.h>
 #include <linux/of_platform.h>
 #include <linux/percpu.h>
-#include <linux/set_memory.h>
 #include <linux/slab.h>
 #include <linux/syscore_ops.h>
 #include <linux/topology.h>
@@ -214,25 +213,13 @@ static gfp_t gfp_flags_quirk;
 static struct page *its_alloc_pages_node(int node, gfp_t gfp,
 					 unsigned int order)
 {
-	struct page *page;
-	int ret = 0;
-
-	page = alloc_pages_node(node, gfp | gfp_flags_quirk, order);
-
-	if (!page)
-		return NULL;
+	struct cc_shared_pages mem;
 
-	ret = set_memory_decrypted((unsigned long)page_address(page),
-				   1 << order);
-	/*
-	 * If set_memory_decrypted() fails then we don't know what state the
-	 * page is in, so we can't free it. Instead we leak it.
-	 * set_memory_decrypted() will already have WARNed.
-	 */
-	if (ret)
+	if (alloc_cc_shared_pages_node(node, gfp | gfp_flags_quirk,
+				       PAGE_SIZE << order, &mem))
 		return NULL;
 
-	return page;
+	return mem.page;
 }
 
 static struct page *its_alloc_pages(gfp_t gfp, unsigned int order)
@@ -242,13 +229,15 @@ static struct page *its_alloc_pages(gfp_t gfp, unsigned int order)
 
 static void its_free_pages(void *addr, unsigned int order)
 {
-	/*
-	 * If the memory cannot be encrypted again then we must leak the pages.
-	 * set_memory_encrypted() will already have WARNed.
-	 */
-	if (set_memory_encrypted((unsigned long)addr, 1 << order))
+	struct cc_shared_layout layout;
+	struct cc_shared_pages mem;
+
+	if (WARN_ON(cc_shared_calc_layout(PAGE_SIZE << order, &layout)))
 		return;
-	free_pages((unsigned long)addr, order);
+
+	mem.page = virt_to_page(addr);
+	mem.shared_size = layout.shared_size;
+	free_cc_shared_pages(&mem);
 }
 
 static struct gen_pool *itt_pool;
@@ -273,7 +262,8 @@ static void *itt_alloc_pool(int node, int size)
 		if (!page)
 			break;
 
-		gen_pool_add(itt_pool, (unsigned long)page_address(page), PAGE_SIZE, node);
+		gen_pool_add(itt_pool, (unsigned long)page_address(page),
+			     cc_shared_granule_size(), node);
 	} while (!addr);
 
 	return (void *)addr;
-- 
2.43.0