From 9f0fc191371843c4fc000a226b0a26b6c059aacd Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sat, 18 May 2024 19:40:19 +0200 Subject: Merging upstream version 6.7.7. Signed-off-by: Daniel Baumann --- Documentation/admin-guide/hw-vuln/mds.rst | 34 +++++++++------------- .../hw-vuln/processor_mmio_stale_data.rst | 13 ++++++++- .../admin-guide/hw-vuln/tsx_async_abort.rst | 33 +++++++++------------ 3 files changed, 38 insertions(+), 42 deletions(-) (limited to 'Documentation/admin-guide/hw-vuln') diff --git a/Documentation/admin-guide/hw-vuln/mds.rst b/Documentation/admin-guide/hw-vuln/mds.rst index 48ca0bd85..48c7b0b72 100644 --- a/Documentation/admin-guide/hw-vuln/mds.rst +++ b/Documentation/admin-guide/hw-vuln/mds.rst @@ -102,9 +102,19 @@ The possible values in this file are: * - 'Vulnerable' - The processor is vulnerable, but no mitigation enabled * - 'Vulnerable: Clear CPU buffers attempted, no microcode' - - The processor is vulnerable but microcode is not updated. - - The mitigation is enabled on a best effort basis. See :ref:`vmwerv` + - The processor is vulnerable but microcode is not updated. The + mitigation is enabled on a best effort basis. + + If the processor is vulnerable but the availability of the microcode + based mitigation mechanism is not advertised via CPUID, the kernel + selects a best effort mitigation mode. This mode invokes the mitigation + instructions without a guarantee that they clear the CPU buffers. + + This is done to address virtualization scenarios where the host has the + microcode update applied, but the hypervisor is not yet updated to + expose the CPUID to the guest. If the host has updated microcode the + protection takes effect; otherwise a few CPU cycles are wasted + pointlessly. * - 'Mitigation: Clear CPU buffers' - The processor is vulnerable and the CPU buffer clearing mitigation is enabled. @@ -119,24 +129,6 @@ to the above information: 'SMT Host state unknown' Kernel runs in a VM, Host SMT state unknown ======================== ============================================ -.. _vmwerv: - -Best effort mitigation mode -^^^^^^^^^^^^^^^^^^^^^^^^^^^ - - If the processor is vulnerable, but the availability of the microcode based - mitigation mechanism is not advertised via CPUID the kernel selects a best - effort mitigation mode. This mode invokes the mitigation instructions - without a guarantee that they clear the CPU buffers. - - This is done to address virtualization scenarios where the host has the - microcode update applied, but the hypervisor is not yet updated to expose - the CPUID to the guest. If the host has updated microcode the protection - takes effect otherwise a few cpu cycles are wasted pointlessly. - - The state in the mds sysfs file reflects this situation accordingly. - - Mitigation mechanism ------------------------- diff --git a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst index c98fd1190..1302fd1b5 100644 --- a/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst +++ b/Documentation/admin-guide/hw-vuln/processor_mmio_stale_data.rst @@ -225,8 +225,19 @@ The possible values in this file are: * - 'Vulnerable' - The processor is vulnerable, but no mitigation enabled * - 'Vulnerable: Clear CPU buffers attempted, no microcode' - - The processor is vulnerable, but microcode is not updated. The + - The processor is vulnerable but microcode is not updated. The mitigation is enabled on a best effort basis. + + If the processor is vulnerable but the availability of the microcode + based mitigation mechanism is not advertised via CPUID, the kernel + selects a best effort mitigation mode. This mode invokes the mitigation + instructions without a guarantee that they clear the CPU buffers. + + This is done to address virtualization scenarios where the host has the + microcode update applied, but the hypervisor is not yet updated to + expose the CPUID to the guest. If the host has updated microcode the + protection takes effect; otherwise a few CPU cycles are wasted + pointlessly. * - 'Mitigation: Clear CPU buffers' - The processor is vulnerable and the CPU buffer clearing mitigation is enabled. diff --git a/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst b/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst index 014167ef8..444f84e22 100644 --- a/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst +++ b/Documentation/admin-guide/hw-vuln/tsx_async_abort.rst @@ -98,7 +98,19 @@ The possible values in this file are: * - 'Vulnerable' - The CPU is affected by this vulnerability and the microcode and kernel mitigation are not applied. * - 'Vulnerable: Clear CPU buffers attempted, no microcode' - - The system tries to clear the buffers but the microcode might not support the operation. + - The processor is vulnerable but microcode is not updated. The + mitigation is enabled on a best effort basis. + + If the processor is vulnerable but the availability of the microcode + based mitigation mechanism is not advertised via CPUID, the kernel + selects a best effort mitigation mode. This mode invokes the mitigation + instructions without a guarantee that they clear the CPU buffers. + + This is done to address virtualization scenarios where the host has the + microcode update applied, but the hypervisor is not yet updated to + expose the CPUID to the guest. If the host has updated microcode the + protection takes effect; otherwise a few CPU cycles are wasted + pointlessly. * - 'Mitigation: Clear CPU buffers' - The microcode has been updated to clear the buffers. TSX is still enabled. * - 'Mitigation: TSX disabled' @@ -106,25 +118,6 @@ The possible values in this file are: * - 'Not affected' - The CPU is not affected by this issue. -.. _ucode_needed: - -Best effort mitigation mode -^^^^^^^^^^^^^^^^^^^^^^^^^^^ - -If the processor is vulnerable, but the availability of the microcode-based -mitigation mechanism is not advertised via CPUID the kernel selects a best -effort mitigation mode. This mode invokes the mitigation instructions -without a guarantee that they clear the CPU buffers. - -This is done to address virtualization scenarios where the host has the -microcode update applied, but the hypervisor is not yet updated to expose the -CPUID to the guest. If the host has updated microcode the protection takes -effect; otherwise a few CPU cycles are wasted pointlessly. - -The state in the tsx_async_abort sysfs file reflects this situation -accordingly. - - Mitigation mechanism -------------------- -- cgit v1.2.3