linux-kernel - [PATCH v2] riscv: mm: don't advertise 1 num

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Message-Id: <20210908173029.1104897-1-vgupta@kernel.org>
Date:   Wed,  8 Sep 2021 10:30:29 -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>,
        Anup Patel <anup@...infault.org>
Subject: [PATCH v2] 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
case.

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

Verified this on Hifive Unmatched.

Reviewed-by: Anup Patel <anup@...infault.org>
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..ea54cc0c9106 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