linux-kernel - [PATCH v2 2/3] x86: Log resource clipping for E820 regions

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Date:   Thu, 14 Apr 2022 13:22:51 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Hans de Goede <hdegoede@...hat.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>
Cc:     Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Myron Stowe <myron.stowe@...hat.com>,
        Juha-Pekka Heikkila <juhapekka.heikkila@...il.com>,
        Benoit Grégoire <benoitg@...us.ca>,
        Hui Wang <hui.wang@...onical.com>,
        Kai-Heng Feng <kai.heng.feng@...onical.com>,
        linux-acpi@...r.kernel.org, linux-pci@...r.kernel.org,
        x86@...nel.org, linux-kernel@...r.kernel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v2 2/3] x86: Log resource clipping for E820 regions

From: Bjorn Helgaas <bhelgaas@...gle.com>

When remove_e820_regions() clips a resource because an E820 region overlaps
it, log a note in dmesg to add in debugging.

Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 arch/x86/kernel/resource.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/resource.c b/arch/x86/kernel/resource.c
index 8ffe68437744..30d524adb012 100644
--- a/arch/x86/kernel/resource.c
+++ b/arch/x86/kernel/resource.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/ioport.h>
+#include <linux/printk.h>
 #include <asm/e820/api.h>
 
 static void resource_clip(struct resource *res, resource_size_t start,
@@ -28,6 +29,7 @@ static void remove_e820_regions(struct resource *avail)
 	int i;
 	struct e820_entry *entry;
 	u64 e820_start, e820_end;
+	struct resource orig = *avail;
 
 	for (i = 0; i < e820_table->nr_entries; i++) {
 		entry = &e820_table->entries[i];
@@ -35,6 +37,11 @@ static void remove_e820_regions(struct resource *avail)
 		e820_end = entry->addr + entry->size - 1;
 
 		resource_clip(avail, e820_start, e820_end);
+		if (orig.start != avail->start || orig.end != avail->end) {
+			pr_info("clipped %pR to %pR for e820 entry [mem %#010Lx-%#010Lx]\n",
+				 &orig, avail, e820_start, e820_end);
+			orig = *avail;
+		}
 	}
 }
 
-- 
2.25.1