linux-kernel - [PATCH 4.4 018/312] MIPS: Fix HTW config on XPA kernel without LPA enabled

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Message-Id: <20200508123125.770053528@linuxfoundation.org>
Date:   Fri,  8 May 2020 14:30:09 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, James Hogan <james.hogan@...tec.com>,
        "Steven J. Hill" <sjhill@...litydiluted.com>,
        Paul Burton <paul.burton@...tec.com>,
        Paul Gortmaker <paul.gortmaker@...driver.com>,
        linux-mips@...ux-mips.org, Ralf Baechle <ralf@...ux-mips.org>
Subject: [PATCH 4.4 018/312] MIPS: Fix HTW config on XPA kernel without LPA enabled

From: James Hogan <james.hogan@...tec.com>

commit 14bc241443e126c62fcbf571b7d4c79740debc58 upstream.

The hardware page table walker (HTW) configuration is broken on XPA
kernels where XPA couldn't be enabled (either nohtw or the hardware
doesn't support it). This is because the PWSize.PTEW field (PTE width)
was only set to 8 bytes (an extra shift of 1) in config_htw_params() if
PageGrain.ELPA (enable large physical addressing) is set. On an XPA
kernel though the size of PTEs is fixed at 8 bytes regardless of whether
XPA could actually be enabled.

Fix the initialisation of this field based on sizeof(pte_t) instead.

Fixes: c5b367835cfc ("MIPS: Add support for XPA.")
Signed-off-by: James Hogan <james.hogan@...tec.com>
Cc: Steven J. Hill <sjhill@...litydiluted.com>
Cc: Paul Burton <paul.burton@...tec.com>
Cc: Paul Gortmaker <paul.gortmaker@...driver.com>
Cc: linux-mips@...ux-mips.org
Cc: linux-kernel@...r.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/13113/
Signed-off-by: Paul Burton <paul.burton@...tec.com>
Signed-off-by: Ralf Baechle <ralf@...ux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/mips/mm/tlbex.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -2329,9 +2329,7 @@ static void config_htw_params(void)
 	if (CONFIG_PGTABLE_LEVELS >= 3)
 		pwsize |= ilog2(PTRS_PER_PMD) << MIPS_PWSIZE_MDW_SHIFT;

-	/* If XPA has been enabled, PTEs are 64-bit in size. */
-	if (config_enabled(CONFIG_64BITS) || (read_c0_pagegrain() & PG_ELPA))
-		pwsize |= 1;
+	pwsize |= ilog2(sizeof(pte_t)/4) << MIPS_PWSIZE_PTEW_SHIFT;

 	write_c0_pwsize(pwsize);