v2:
- Added patch to disable TSX development mode (Andrew, Boris)
- Rebased to v5.17-rc7
v1: https://lore.kernel.org/lkml/5bd785a1d6ea0b572250add0c6617b4504bc24d1.1644440311.git.pawan.kumar.gupta@linux.intel.com/
Hi,
After a recent microcode update some Intel processors will always abort
Transactional Synchronization Extensions (TSX) transactions [*]. On
these processors a new CPUID bit,
CPUID.07H.0H.EDX[11](RTM_ALWAYS_ABORT), will be enumerated to indicate
that the loaded microcode is forcing Restricted Transactional Memory
(RTM) abort. If the processor enumerated support for RTM previously, the
CPUID enumeration bits for TSX (CPUID.RTM and CPUID.HLE) continue to be
set by default after the microcode update.
First patch in this series clears CPUID.RTM and CPUID.HLE so that
userspace doesn't enumerate TSX feature.
Microcode also added support to re-enable TSX for development purpose,
doing so is not recommended for production deployments, because MD_CLEAR
flows for the mitigation of TSX Asynchronous Abort (TAA) may not be
effective on these processors when TSX is enabled with updated
microcode.
Second patch unconditionally disables this TSX development mode, in case
it was enabled by the software running before kernel boot.
Thanks,
Pawan
[*] Intel Transactional Synchronization Extension (Intel TSX) Disable Update for Selected Processors
https://cdrdv2.intel.com/v1/dl/getContent/643557
Pawan Gupta (2):
x86/tsx: Use MSR_TSX_CTRL to clear CPUID bits
x86/tsx: Disable TSX development mode at boot
arch/x86/include/asm/msr-index.h | 4 +-
arch/x86/kernel/cpu/cpu.h | 1 +
arch/x86/kernel/cpu/intel.c | 5 ++
arch/x86/kernel/cpu/tsx.c | 88 ++++++++++++++++++++++++--
tools/arch/x86/include/asm/msr-index.h | 4 +-
5 files changed, 91 insertions(+), 11 deletions(-)
base-commit: ffb217a13a2eaf6d5bd974fc83036a53ca69f1e2
--
2.25.1
Hi Boris and others,
On Thu, Mar 10, 2022 at 01:59:47PM -0800, Pawan Gupta wrote:
>v2:
>- Added patch to disable TSX development mode (Andrew, Boris)
>- Rebased to v5.17-rc7
>
>v1: https://lore.kernel.org/lkml/5bd785a1d6ea0b572250add0c6617b4504bc24d1.1644440311.git.pawan.kumar.gupta@linux.intel.com/
>
>Hi,
>
>After a recent microcode update some Intel processors will always abort
>Transactional Synchronization Extensions (TSX) transactions [*]. On
>these processors a new CPUID bit,
>CPUID.07H.0H.EDX[11](RTM_ALWAYS_ABORT), will be enumerated to indicate
>that the loaded microcode is forcing Restricted Transactional Memory
>(RTM) abort. If the processor enumerated support for RTM previously, the
>CPUID enumeration bits for TSX (CPUID.RTM and CPUID.HLE) continue to be
>set by default after the microcode update.
>
>First patch in this series clears CPUID.RTM and CPUID.HLE so that
>userspace doesn't enumerate TSX feature.
>
>Microcode also added support to re-enable TSX for development purpose,
>doing so is not recommended for production deployments, because MD_CLEAR
>flows for the mitigation of TSX Asynchronous Abort (TAA) may not be
>effective on these processors when TSX is enabled with updated
>microcode.
>
>Second patch unconditionally disables this TSX development mode, in case
>it was enabled by the software running before kernel boot.
>
>Thanks,
>Pawan
>
>[*] Intel Transactional Synchronization Extension (Intel TSX) Disable Update for Selected Processors
> https://cdrdv2.intel.com/v1/dl/getContent/643557
>
>Pawan Gupta (2):
> x86/tsx: Use MSR_TSX_CTRL to clear CPUID bits
> x86/tsx: Disable TSX development mode at boot
I am hoping to get some feedback on v2. Are these patches looking okay?
Thanks,
Pawan