Thanks Ingo, but we may have to reconsider whether cpu_has_xfeatures works in this place https://lore.kernel.org/all/1b8745e0-ae80-4add-b015-affdaa69b369@intel.com/

The current code might be accidentally disabling PKU on other PKU-compatible environments?

2025年3月20日(木) 6:39 Ingo Molnar mingo@kernel.org:

• Akihiro Suda suda.gitsendemail@gmail.com wrote:

...

Even when X86_FEATURE_PKU and X86_FEATURE_OSPKE are available, XFEATURE_PKRU can be missing. In such a case, pkeys has to be disabled to avoid hanging up.

WARNING: CPU: 0 PID: 1 at arch/x86/kernel/fpu/xstate.c:1003 get_xsave_addr_user+0x28/0x40 (...) Call Trace:

<TASK> ? get_xsave_addr_user+0x28/0x40 ? __warn.cold+0x8e/0xea ? get_xsave_addr_user+0x28/0x40 ? report_bug+0xff/0x140 ? handle_bug+0x3b/0x70 ? exc_invalid_op+0x17/0x70 ? asm_exc_invalid_op+0x1a/0x20 ? get_xsave_addr_user+0x28/0x40 copy_fpstate_to_sigframe+0x1be/0x380 ? __put_user_8+0x11/0x20 get_sigframe+0xf1/0x280 x64_setup_rt_frame+0x67/0x2c0 arch_do_signal_or_restart+0x1b3/0x240 syscall_exit_to_user_mode+0xb0/0x130 do_syscall_64+0xab/0x1a0 entry_SYSCALL_64_after_hwframe+0x77/0x7f

This fix is known to be needed on Apple Virtualization. Tested with macOS 13.5.2 running on MacBook Pro 2020 with Intel(R) Core(TM) i7-1068NG7 CPU @ 2.30GHz.

Fixes: 70044df250d0 ("x86/pkeys: Update PKRU to enable all pkeys before XSAVE") Link: https://lore.kernel.org/regressions/CAG8fp8QvH71Wi_y7b7tgFp7knK38rfrF7rRHh-g... Link: https://github.com/lima-vm/lima/issues/3334

Signed-off-by: Akihiro Suda akihiro.suda.cz@hco.ntt.co.jp

arch/x86/kernel/cpu/common.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index e9464fe411ac..4c2c268af214 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -517,7 +517,8 @@ static bool pku_disabled; static __always_inline void setup_pku(struct cpuinfo_x86 *c) { if (c == &boot_cpu_data) {

•         if (pku_disabled || !cpu_feature_enabled(X86_FEATURE_PKU))
  

•         if (pku_disabled || !cpu_feature_enabled(X86_FEATURE_PKU) ||
  

•             !cpu_has_xfeatures(XFEATURE_PKRU, NULL))
                  return;
  

Note that silent quirks are counterproductive, as they don't give VM vendors any incentives to fix their VM for such bugs.

So I changed your quirk to be:

--- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -519,6 +519,17 @@ static __always_inline void setup_pku(struct cpuinfo_x86 *c) if (c == &boot_cpu_data) { if (pku_disabled || !cpu_feature_enabled(X86_FEATURE_PKU)) return;

•           if (!cpu_has_xfeatures(XFEATURE_PKRU, NULL)) {
  

•                   /*
  

•                    * Missing XFEATURE_PKRU is not really a valid CPU
  

•                    * configuration at this point, but apparently
  

•                    * Apple Virtualization is affected by this,
  

•                    * so return with a FW warning instead of crashing
  

•                    * the bootup:
  

•                    */
  

•                   WARN_ONCE(1, FW_BUG "Invalid XFEATURE_PKRU configuration.\n");
  

•                   return;
  

•           }
            /*
             * Setting CR4.PKE will cause the X86_FEATURE_OSPKE cpuid
             * bit to be set.  Enforce it.
  
  

This is noisy in the syslog, but it's a WARN_ONCE() and it doesn't crash the bootup.

Thanks,

    Ingo