Patch "i2c: designware: Fix corrupted memory seen in the ISR" has been added to the 6.1-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    i2c: designware: Fix corrupted memory seen in the ISR

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     i2c-designware-fix-corrupted-memory-seen-in-the-isr.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 19686fbc1a118738c7acf12e034b15d139c054fa
Author: Jan Bottorff <janb@xxxxxxxxxxxxxxxxxxxxxx>
Date:   Thu Nov 9 03:19:27 2023 +0000

    i2c: designware: Fix corrupted memory seen in the ISR
    
    [ Upstream commit f726eaa787e9f9bc858c902d18a09af6bcbfcdaf ]
    
    When running on a many core ARM64 server, errors were
    happening in the ISR that looked like corrupted memory. These
    corruptions would fix themselves if small delays were inserted
    in the ISR. Errors reported by the driver included "i2c_designware
    APMC0D0F:00: i2c_dw_xfer_msg: invalid target address" and
    "i2c_designware APMC0D0F:00:controller timed out" during
    in-band IPMI SSIF stress tests.
    
    The problem was determined to be memory writes in the driver were not
    becoming visible to all cores when execution rapidly shifted between
    cores, like when a register write immediately triggers an ISR.
    Processors with weak memory ordering, like ARM64, make no
    guarantees about the order normal memory writes become globally
    visible, unless barrier instructions are used to control ordering.
    
    To solve this, regmap accessor functions configured by this driver
    were changed to use non-relaxed forms of the low-level register
    access functions, which include a barrier on platforms that require
    it. This assures memory writes before a controller register access are
    visible to all cores. The community concluded defaulting to correct
    operation outweighed defaulting to the small performance gains from
    using relaxed access functions. Being a low speed device added weight to
    this choice of default register access behavior.
    
    Signed-off-by: Jan Bottorff <janb@xxxxxxxxxxxxxxxxxxxxxx>
    Acked-by: Jarkko Nikula <jarkko.nikula@xxxxxxxxxxxxxxx>
    Tested-by: Serge Semin <fancer.lancer@xxxxxxxxx>
    Reviewed-by: Serge Semin <fancer.lancer@xxxxxxxxx>
    Signed-off-by: Wolfram Sang <wsa@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
index 6fdb25a5f8016..ad98c85ec2e7a 100644
--- a/drivers/i2c/busses/i2c-designware-common.c
+++ b/drivers/i2c/busses/i2c-designware-common.c
@@ -63,7 +63,7 @@ static int dw_reg_read(void *context, unsigned int reg, unsigned int *val)
 {
 	struct dw_i2c_dev *dev = context;
 
-	*val = readl_relaxed(dev->base + reg);
+	*val = readl(dev->base + reg);
 
 	return 0;
 }
@@ -72,7 +72,7 @@ static int dw_reg_write(void *context, unsigned int reg, unsigned int val)
 {
 	struct dw_i2c_dev *dev = context;
 
-	writel_relaxed(val, dev->base + reg);
+	writel(val, dev->base + reg);
 
 	return 0;
 }
@@ -81,7 +81,7 @@ static int dw_reg_read_swab(void *context, unsigned int reg, unsigned int *val)
 {
 	struct dw_i2c_dev *dev = context;
 
-	*val = swab32(readl_relaxed(dev->base + reg));
+	*val = swab32(readl(dev->base + reg));
 
 	return 0;
 }
@@ -90,7 +90,7 @@ static int dw_reg_write_swab(void *context, unsigned int reg, unsigned int val)
 {
 	struct dw_i2c_dev *dev = context;
 
-	writel_relaxed(swab32(val), dev->base + reg);
+	writel(swab32(val), dev->base + reg);
 
 	return 0;
 }
@@ -99,8 +99,8 @@ static int dw_reg_read_word(void *context, unsigned int reg, unsigned int *val)
 {
 	struct dw_i2c_dev *dev = context;
 
-	*val = readw_relaxed(dev->base + reg) |
-		(readw_relaxed(dev->base + reg + 2) << 16);
+	*val = readw(dev->base + reg) |
+		(readw(dev->base + reg + 2) << 16);
 
 	return 0;
 }
@@ -109,8 +109,8 @@ static int dw_reg_write_word(void *context, unsigned int reg, unsigned int val)
 {
 	struct dw_i2c_dev *dev = context;
 
-	writew_relaxed(val, dev->base + reg);
-	writew_relaxed(val >> 16, dev->base + reg + 2);
+	writew(val, dev->base + reg);
+	writew(val >> 16, dev->base + reg + 2);
 
 	return 0;
 }