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* [PATCH v2] iscsi_ibft: Fix finding the iBFT under Xen Dom 0
@ 2023-05-30 15:01 Ross Lagerwall
  2023-06-01 16:57 ` Dave Hansen
  0 siblings, 1 reply; 6+ messages in thread
From: Ross Lagerwall @ 2023-05-30 15:01 UTC (permalink / raw)
  To: linux-kernel, xen-devel
  Cc: Jan Beulich, Thomas Gleixner, Ingo Molnar, Borislav Petkov,
	Dave Hansen, x86, Juergen Gross, Boris Ostrovsky, Peter Jones,
	Konrad Rzeszutek Wilk, Ross Lagerwall

Since firmware doesn't indicate the iBFT in the E820, add a reserved
region so that it gets identity mapped when running as Dom 0 so that it
is possible to search for it. Move the call to reserve_ibft_region()
later so that it is called after the Xen identity mapping adjustments
are applied.

Finally, instead of using isa_bus_to_virt() which doesn't do the right
thing under Xen, use early_memremap() like the dmi_scan code does.

Signed-off-by: Ross Lagerwall <ross.lagerwall@citrix.com>
---

In v2:
* Fix style issue
* Make added e820 entry conditional on ISCSI_IBFT_FIND

 arch/x86/kernel/setup.c            |  2 +-
 arch/x86/xen/setup.c               | 27 ++++++++++++++++++---------
 drivers/firmware/iscsi_ibft_find.c | 24 +++++++++++++++++-------
 3 files changed, 36 insertions(+), 17 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 16babff771bd..616b80507abd 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -796,7 +796,6 @@ static void __init early_reserve_memory(void)
 
 	memblock_x86_reserve_range_setup_data();
 
-	reserve_ibft_region();
 	reserve_bios_regions();
 	trim_snb_memory();
 }
@@ -1032,6 +1031,7 @@ void __init setup_arch(char **cmdline_p)
 	if (efi_enabled(EFI_BOOT))
 		efi_init();
 
+	reserve_ibft_region();
 	dmi_setup();
 
 	/*
diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index c2be3efb2ba0..07c7039bdd66 100644
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -764,17 +764,26 @@ char * __init xen_memory_setup(void)
 	BUG_ON(memmap.nr_entries == 0);
 	xen_e820_table.nr_entries = memmap.nr_entries;
 
-	/*
-	 * Xen won't allow a 1:1 mapping to be created to UNUSABLE
-	 * regions, so if we're using the machine memory map leave the
-	 * region as RAM as it is in the pseudo-physical map.
-	 *
-	 * UNUSABLE regions in domUs are not handled and will need
-	 * a patch in the future.
-	 */
-	if (xen_initial_domain())
+	if (xen_initial_domain()) {
+		/*
+		 * Xen won't allow a 1:1 mapping to be created to UNUSABLE
+		 * regions, so if we're using the machine memory map leave the
+		 * region as RAM as it is in the pseudo-physical map.
+		 *
+		 * UNUSABLE regions in domUs are not handled and will need
+		 * a patch in the future.
+		 */
 		xen_ignore_unusable();
 
+#ifdef CONFIG_ISCSI_IBFT_FIND
+		/* Reserve 0.5 MiB to 1 MiB region so iBFT can be found */
+		xen_e820_table.entries[xen_e820_table.nr_entries].addr = 0x80000;
+		xen_e820_table.entries[xen_e820_table.nr_entries].size = 0x80000;
+		xen_e820_table.entries[xen_e820_table.nr_entries].type = E820_TYPE_RESERVED;
+		xen_e820_table.nr_entries++;
+#endif
+	}
+
 	/* Make sure the Xen-supplied memory map is well-ordered. */
 	e820__update_table(&xen_e820_table);
 
diff --git a/drivers/firmware/iscsi_ibft_find.c b/drivers/firmware/iscsi_ibft_find.c
index 94b49ccd23ac..e3c1449987dd 100644
--- a/drivers/firmware/iscsi_ibft_find.c
+++ b/drivers/firmware/iscsi_ibft_find.c
@@ -52,9 +52,9 @@ static const struct {
  */
 void __init reserve_ibft_region(void)
 {
-	unsigned long pos;
+	unsigned long pos, virt_pos = 0;
 	unsigned int len = 0;
-	void *virt;
+	void *virt = NULL;
 	int i;
 
 	ibft_phys_addr = 0;
@@ -70,13 +70,20 @@ void __init reserve_ibft_region(void)
 		 * so skip that area */
 		if (pos == VGA_MEM)
 			pos += VGA_SIZE;
-		virt = isa_bus_to_virt(pos);
+
+		/* Map page by page */
+		if (offset_in_page(pos) == 0) {
+			if (virt)
+				early_memunmap(virt, PAGE_SIZE);
+			virt = early_memremap_ro(pos, PAGE_SIZE);
+			virt_pos = pos;
+		}
 
 		for (i = 0; i < ARRAY_SIZE(ibft_signs); i++) {
-			if (memcmp(virt, ibft_signs[i].sign, IBFT_SIGN_LEN) ==
-			    0) {
+			if (memcmp(virt + (pos - virt_pos), ibft_signs[i].sign,
+				   IBFT_SIGN_LEN) == 0) {
 				unsigned long *addr =
-				    (unsigned long *)isa_bus_to_virt(pos + 4);
+				    (unsigned long *)(virt + pos - virt_pos + 4);
 				len = *addr;
 				/* if the length of the table extends past 1M,
 				 * the table cannot be valid. */
@@ -84,9 +91,12 @@ void __init reserve_ibft_region(void)
 					ibft_phys_addr = pos;
 					memblock_reserve(ibft_phys_addr, PAGE_ALIGN(len));
 					pr_info("iBFT found at %pa.\n", &ibft_phys_addr);
-					return;
+					goto out;
 				}
 			}
 		}
 	}
+
+out:
+	early_memunmap(virt, PAGE_SIZE);
 }
-- 
2.31.1


^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-06-05 10:28 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2023-05-30 15:01 [PATCH v2] iscsi_ibft: Fix finding the iBFT under Xen Dom 0 Ross Lagerwall
2023-06-01 16:57 ` Dave Hansen
2023-06-01 17:08   ` Dave Hansen
2023-06-01 18:05     ` Andrew Cooper
2023-06-02  6:06   ` Juergen Gross
2023-06-05 10:27   ` Ross Lagerwall

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