linux-kernel - [PATCH -fixes v4 0/3] riscv: cbo.zero fixes

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Message-ID: <20240228065559.3434837-1-samuel.holland@sifive.com>
Date: Tue, 27 Feb 2024 22:55:32 -0800
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>
Cc: Andrew Jones <ajones@...tanamicro.com>,
	linux-kernel@...r.kernel.org,
	Conor Dooley <conor@...nel.org>,
	Alexandre Ghiti <alex@...ti.fr>,
	linux-riscv@...ts.infradead.org,
	Stefan O'Rear <sorear@...tmail.com>,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH -fixes v4 0/3] riscv: cbo.zero fixes

This series fixes a couple of issues related to using the cbo.zero
instruction in userspace. The first patch fixes a bug where the wrong
enable bit gets set if the kernel is running in M-mode. The remaining
patches fix a bug where the enable bit gets reset to its default value
after a nonretentive idle state. I have hardware which reproduces this:

Before this series:
  $ tools/testing/selftests/riscv/hwprobe/cbo
  TAP version 13
  1..3
  ok 1 Zicboz block size
  # Zicboz block size: 64
  Illegal instruction

After applying this series:
  $ tools/testing/selftests/riscv/hwprobe/cbo
  TAP version 13
  1..3
  ok 1 Zicboz block size
  # Zicboz block size: 64
  ok 2 cbo.zero
  ok 3 cbo.zero check
  # Totals: pass:3 fail:0 xfail:0 xpass:0 skip:0 error:0

Changes in v4:
 - Add a patch defining and setting the Xlinuxenvcfg ISA extension bit
 - Check for Xlinuxenvcfg instead of Zicboz

Changes in v3:
 - Drop patches added in v2
 - Check for Zicboz instead of the privileged ISA version

Changes in v2:
 - Add patches to allow parsing the privileged ISA version from the DT
 - Check for privileged ISA v1.12 instead of the specific CSR
 - Use riscv_has_extension_likely() instead of new ALTERNATIVE()s

Samuel Holland (3):
  riscv: Fix enabling cbo.zero when running in M-mode
  riscv: Add a custom ISA extension for the [ms]envcfg CSR
  riscv: Save/restore envcfg CSR during CPU suspend

 arch/riscv/include/asm/csr.h     |  2 ++
 arch/riscv/include/asm/hwcap.h   |  2 ++
 arch/riscv/include/asm/suspend.h |  1 +
 arch/riscv/kernel/cpufeature.c   | 16 +++++++++++++---
 arch/riscv/kernel/suspend.c      |  4 ++++
 5 files changed, 22 insertions(+), 3 deletions(-)

-- 
2.43.1