linux-kernel - [PATCH] riscv: mm: don't advertise 1 num

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Date:   Tue,  7 Sep 2021 13:02:54 -0700
From:   Vineet Gupta <vgupta@...nel.org>
To:     Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Anup Patel <anup.patel@....com>,
        Jisheng Zhang <jszhang@...nel.org>,
        Guo Ren <guoren@...ux.alibaba.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>
Cc:     linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Vineet Gupta <vgupta@...nel.org>
Subject: [PATCH] riscv: mm: don't advertise 1 num_asid for 0 asid bits

Even if mmu doesn't support ASID, current code calculates @num_asids=1
which is misleading, so avoid setting any asid related variables in such
a case.

Also while here, print the number of asid bits discovered even for the
disabled case.

Verified this on Hifive Unmatched.

Signed-off-by: Vineet Gupta <vgupta@...nel.org>
---
 arch/riscv/mm/context.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c
index ee3459cb6750..c8c6f8831a3b 100644
--- a/arch/riscv/mm/context.c
+++ b/arch/riscv/mm/context.c
@@ -233,8 +233,10 @@ static int __init asids_init(void)
 	local_flush_tlb_all();
 
 	/* Pre-compute ASID details */
-	num_asids = 1 << asid_bits;
-	asid_mask = num_asids - 1;
+	if (asid_bits) {
+		num_asids = 1 << asid_bits;
+		asid_mask = num_asids - 1;
+	}
 
 	/*
 	 * Use ASID allocator only if number of HW ASIDs are
@@ -255,7 +257,7 @@ static int __init asids_init(void)
 		pr_info("ASID allocator using %lu bits (%lu entries)\n",
 			asid_bits, num_asids);
 	} else {
-		pr_info("ASID allocator disabled\n");
+		pr_info("ASID allocator disabled: %lu bits\n", asid_bits);
 	}
 
 	return 0;
-- 
2.30.2