linux-kernel - [PATCH] LoongArch: Don't panic if no valid cache info for PCI

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Message-ID: <20251120082039.2293136-1-chenhuacai@loongson.cn>
Date: Thu, 20 Nov 2025 16:20:39 +0800
From: Huacai Chen <chenhuacai@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: loongarch@...ts.linux.dev,
	Xuefeng Li <lixuefeng@...ngson.cn>,
	Guo Ren <guoren@...nel.org>,
	Xuerui Wang <kernel@...0n.name>,
	Jiaxun Yang <jiaxun.yang@...goat.com>,
	linux-kernel@...r.kernel.org,
	Huacai Chen <chenhuacai@...ngson.cn>,
	stable@...r.kernel.org
Subject: [PATCH] LoongArch: Don't panic if no valid cache info for PCI

If there is no valid cache info detected (may happen in virtual machine)
for pci_dfl_cache_line_size, kernel shouldn't panic. Because in the PCI
core it will be evaluated to (L1_CACHE_BYTES >> 2).

Cc: <stable@...r.kernel.org>
Signed-off-by: Jiaxun Yang <jiaxun.yang@...goat.com>
Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 arch/loongarch/pci/pci.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/loongarch/pci/pci.c b/arch/loongarch/pci/pci.c
index 5bc9627a6cf9..d9fc5d520b37 100644
--- a/arch/loongarch/pci/pci.c
+++ b/arch/loongarch/pci/pci.c
@@ -50,11 +50,11 @@ static int __init pcibios_init(void)
 	 */
 	lsize = cpu_last_level_cache_line_size();
 
-	BUG_ON(!lsize);
+	if (lsize) {
+		pci_dfl_cache_line_size = lsize >> 2;
 
-	pci_dfl_cache_line_size = lsize >> 2;
-
-	pr_debug("PCI: pci_cache_line_size set to %d bytes\n", lsize);
+		pr_debug("PCI: pci_cache_line_size set to %d bytes\n", lsize);
+	}
 
 	return 0;
 }
-- 
2.47.3