linux-kernel - [PATCH v2 3/6] efi/fake_mem: Arrange for a resource entry per efi_fake

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Message-ID: <158489356105.1457606.7319511363791228163.stgit@dwillia2-desk3.amr.corp.intel.com>
Date:   Sun, 22 Mar 2020 09:12:41 -0700
From:   Dan Williams <dan.j.williams@...el.com>
To:     linux-acpi@...r.kernel.org
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Ard Biesheuvel <ardb@...nel.org>, peterz@...radead.org,
        dave.hansen@...ux.intel.com, ard.biesheuvel@...aro.org,
        linux-nvdimm@...ts.01.org, linux-kernel@...r.kernel.org,
        x86@...nel.org, joao.m.martins@...cle.com
Subject: [PATCH v2 3/6] efi/fake_mem: Arrange for a resource entry per
 efi_fake_mem instance

In preparation for attaching a platform device per iomem resource teach
the efi_fake_mem code to create an e820 entry per instance. Similar to
E820_TYPE_PRAM, bypass merging resource when the e820 map is sanitized.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: x86@...nel.org
Acked-by: Ard Biesheuvel <ardb@...nel.org>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
---
 arch/x86/kernel/e820.c              |   16 +++++++++++++++-
 drivers/firmware/efi/x86_fake_mem.c |   12 +++++++++---
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c
index c5399e80c59c..96babb3a6629 100644
--- a/arch/x86/kernel/e820.c
+++ b/arch/x86/kernel/e820.c
@@ -305,6 +305,20 @@ static int __init cpcompare(const void *a, const void *b)
 	return (ap->addr != ap->entry->addr) - (bp->addr != bp->entry->addr);
 }
 
+static bool e820_nomerge(enum e820_type type)
+{
+	/*
+	 * These types may indicate distinct platform ranges aligned to
+	 * numa node, protection domain, performance domain, or other
+	 * boundaries. Do not merge them.
+	 */
+	if (type == E820_TYPE_PRAM)
+		return true;
+	if (type == E820_TYPE_SOFT_RESERVED)
+		return true;
+	return false;
+}
+
 int __init e820__update_table(struct e820_table *table)
 {
 	struct e820_entry *entries = table->entries;
@@ -380,7 +394,7 @@ int __init e820__update_table(struct e820_table *table)
 		}
 
 		/* Continue building up new map based on this information: */
-		if (current_type != last_type || current_type == E820_TYPE_PRAM) {
+		if (current_type != last_type || e820_nomerge(current_type)) {
 			if (last_type != 0)	 {
 				new_entries[new_nr_entries].size = change_point[chg_idx]->addr - last_addr;
 				/* Move forward only if the new size was non-zero: */
diff --git a/drivers/firmware/efi/x86_fake_mem.c b/drivers/firmware/efi/x86_fake_mem.c
index e5d6d5a1b240..0bafcc1bb0f6 100644
--- a/drivers/firmware/efi/x86_fake_mem.c
+++ b/drivers/firmware/efi/x86_fake_mem.c
@@ -38,7 +38,7 @@ void __init efi_fake_memmap_early(void)
 		m_start = mem->range.start;
 		m_end = mem->range.end;
 		for_each_efi_memory_desc(md) {
-			u64 start, end;
+			u64 start, end, size;
 
 			if (md->type != EFI_CONVENTIONAL_MEMORY)
 				continue;
@@ -58,11 +58,17 @@ void __init efi_fake_memmap_early(void)
 			 */
 			start = max(start, m_start);
 			end = min(end, m_end);
+			size = end - start + 1;
 
 			if (end <= start)
 				continue;
-			e820__range_update(start, end - start + 1, E820_TYPE_RAM,
-					E820_TYPE_SOFT_RESERVED);
+
+			/*
+			 * Ensure each efi_fake_mem instance results in
+			 * a unique e820 resource
+			 */
+			e820__range_remove(start, size, E820_TYPE_RAM, 1);
+			e820__range_add(start, size, E820_TYPE_SOFT_RESERVED);
 			e820__update_table(e820_table);
 		}
 	}