diff options
| author | Sohil Mehta <[email protected]> | 2021-05-25 16:57:37 -0700 |
|---|---|---|
| committer | Sohil Mehta <[email protected]> | 2021-09-12 19:22:16 -0700 |
| commit | fe39183e5155c84c72150225c785a36f59b62aa2 (patch) | |
| tree | e16525072954154e2aea79fcd8ffca604ab6f31c /Documentation | |
| parent | 8aa587d192bbe526ff3cb945f8a267dcd8c6942b (diff) | |
x86/cpu: Enumerate User Interrupts support
User Interrupts support including user IPIs is enumerated through cpuid.
The 'uintr' flag in /proc/cpuinfo can be used to identify it. The
recommended mechanism for user applications to detect support is calling
the uintr related syscalls.
Use CONFIG_X86_USER_INTERRUPTS to compile with User Interrupts support.
The feature can be disabled at boot time using the 'nouintr' kernel
parameter.
SENDUIPI is a special ring-3 instruction that makes a supervisor mode
memory access to the UPID and UITT memory. Currently, KPTI needs to be
off for User IPIs to work. Processors that support user interrupts are
not affected by Meltdown so the auto mode of KPTI will default to off.
Users who want to force enable KPTI will need to wait for a later
version of this patch series that is compatible with KPTI. We need to
allocate the UPID and UITT structures from a special memory region that
has supervisor access but it is mapped into userspace. The plan is to
implement a mechanism similar to LDT.
Signed-off-by: Jacob Pan <[email protected]>
Signed-off-by: Sohil Mehta <[email protected]>
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 91ba391f9b32..471e82be87ff 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3288,6 +3288,8 @@ nofsgsbase [X86] Disables FSGSBASE instructions. + nouintr [X86-64] Disables User Interrupts support. + no_console_suspend [HW] Never suspend the console Disable suspending of consoles during suspend and |