kernel/linux.git/arch/x86/include/asm/processor.h, branch v6.12.80

x86: make get_cpu_vendor() accessible from Xen code

2024-12-19T17:13:23+00:00

commit efbcd61d9bebb771c836a3b8bfced8165633db7c upstream. In order to be able to differentiate between AMD and Intel based systems for very early hypercalls without having to rely on the Xen hypercall page, make get_cpu_vendor() non-static. Refactor early_cpu_init() for the same reason by splitting out the loop initializing cpu_devs() into an externally callable function. This is part of XSA-466 / CVE-2024-53241. Reported-by: Andrew Cooper Signed-off-by: Juergen Gross Signed-off-by: Greg Kroah-Hartman

Merge tag 'x86-fred-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-09-17T12:55:59+00:00

Pull x86 FRED updates from Thomas Gleixner: - Enable FRED right after init_mem_mapping() because at that point the early IDT fault handler is replaced by the real fault handler. The real fault handler retrieves the faulting address from the stack frame and not from CR2 when the FRED feature is set. But that obviously only works when FRED is enabled in the CPU as well. - Set SS to __KERNEL_DS when enabling FRED to prevent a corner case where ERETS can observe a SS mismatch and raises a #GP. * tag 'x86-fred-2024-09-17' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/entry: Set FRED RSP0 on return to userspace instead of context switch x86/msr: Switch between WRMSRNS and WRMSR with the alternatives mechanism x86/entry: Test ti_work for zero before processing individual bits x86/fred: Set SS to __KERNEL_DS when enabling FRED x86/fred: Enable FRED right after init_mem_mapping() x86/fred: Move FRED RSP initialization into a separate function x86/fred: Parse cmdline param "fred=" in cpu_parse_early_param()

x86/amd: Rename amd_get_highest_perf() to amd_get_boost_ratio_numerator()

2024-09-11T15:23:22+00:00

The function name is ambiguous because it returns an intermediate value for calculating maximum frequency rather than the CPPC 'Highest Perf' register. Rename the function to clarify its use and allow the function to return errors. Adjust the consumer in acpi-cpufreq to catch errors. Reviewed-by: Gautham R. Shenoy Signed-off-by: Mario Limonciello

x86/fred: Enable FRED right after init_mem_mapping()

2024-08-13T19:59:21+00:00

On 64-bit init_mem_mapping() relies on the minimal page fault handler provided by the early IDT mechanism. The real page fault handler is installed right afterwards into the IDT. This is problematic on CPUs which have X86_FEATURE_FRED set because the real page fault handler retrieves the faulting address from the FRED exception stack frame and not from CR2, but that does obviously not work when FRED is not yet enabled in the CPU. To prevent this enable FRED right after init_mem_mapping() without interrupt stacks. Those are enabled later in trap_init() after the CPU entry area is set up. [ tglx: Encapsulate the FRED details ] Fixes: 14619d912b65 ("x86/fred: FRED entry/exit and dispatch code") Reported-by: Hou Wenlong Suggested-by: Thomas Gleixner Signed-off-by: Xin Li (Intel) Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/all/20240709154048.3543361-4-xin@zytor.com

x86/CPU/AMD: Always inline amd_clear_divider()

2024-06-13T12:40:29+00:00

The routine is used on syscall exit and on non-AMD CPUs is guaranteed to be empty. It probably does not need to be a function call even on CPUs which do need the mitigation. [ bp: Make sure it is always inlined so that noinstr marking works. ] Signed-off-by: Mateusz Guzik Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20240613082637.659133-1-mjguzik@gmail.com

Merge tag 'x86-cpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-05-14T01:44:44+00:00

Pull x86 cpu updates from Ingo Molnar: - Rework the x86 CPU vendor/family/model code: introduce the 'VFM' value that is an 8+8+8 bit concatenation of the vendor/family/model value, and add macros that work on VFM values. This simplifies the addition of new Intel models & families, and simplifies existing enumeration & quirk code. - Add support for the AMD 0x80000026 leaf, to better parse topology information - Optimize the NUMA allocation layout of more per-CPU data structures - Improve the workaround for AMD erratum 1386 - Clear TME from /proc/cpuinfo as well, when disabled by the firmware - Improve x86 self-tests - Extend the mce_record tracepoint with the ::ppin and ::microcode fields - Implement recovery for MCE errors in TDX/SEAM non-root mode - Misc cleanups and fixes * tag 'x86-cpu-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits) x86/mm: Switch to new Intel CPU model defines x86/tsc_msr: Switch to new Intel CPU model defines x86/tsc: Switch to new Intel CPU model defines x86/cpu: Switch to new Intel CPU model defines x86/resctrl: Switch to new Intel CPU model defines x86/microcode/intel: Switch to new Intel CPU model defines x86/mce: Switch to new Intel CPU model defines x86/cpu: Switch to new Intel CPU model defines x86/cpu/intel_epb: Switch to new Intel CPU model defines x86/aperfmperf: Switch to new Intel CPU model defines x86/apic: Switch to new Intel CPU model defines perf/x86/msr: Switch to new Intel CPU model defines perf/x86/intel/uncore: Switch to new Intel CPU model defines perf/x86/intel/pt: Switch to new Intel CPU model defines perf/x86/lbr: Switch to new Intel CPU model defines perf/x86/intel/cstate: Switch to new Intel CPU model defines x86/bugs: Switch to new Intel CPU model defines x86/bugs: Switch to new Intel CPU model defines x86/cpu/vfm: Update arch/x86/include/asm/intel-family.h x86/cpu/vfm: Add new macros to work with (vendor/family/model) values ...

Merge tag 'x86-boot-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-05-14T00:50:36+00:00

Pull x86 boot updates from Ingo Molnar: - Move the kernel cmdline setup earlier in the boot process (again), to address a split_lock_detect= boot parameter bug - Ignore relocations in .notes sections - Simplify boot stack setup - Re-introduce a bootloader quirk wrt CR4 handling - Miscellaneous cleanups & fixes * tag 'x86-boot-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/boot/64: Clear most of CR4 in startup_64(), except PAE, MCE and LA57 x86/boot: Move kernel cmdline setup earlier in the boot process (again) x86/build: Clean up arch/x86/tools/relocs.c a bit x86/boot: Ignore relocations in .notes sections in walk_relocs() too x86: Rename __{start,end}_init_task to __{start,end}_init_stack x86/boot: Simplify boot stack setup

Merge tag 'x86-asm-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2024-05-14T00:36:32+00:00

Pull x86 asm updates from Ingo Molnar: - Clean up & fix asm() operand modifiers & constraints - Misc cleanups * tag 'x86-asm-2024-05-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/alternatives: Remove a superfluous newline in _static_cpu_has() x86/asm/64: Clean up memset16(), memset32(), memset64() assembly constraints in x86/asm: Use "m" operand constraint in WRUSSQ asm template x86/asm: Use %a instead of %P operand modifier in asm templates x86/asm: Use %c/%n instead of %P operand modifier in asm templates x86/asm: Remove %P operand modifier from altinstr asm templates

x86/mm: Remove broken vsyscall emulation code from the page fault code

2024-05-01T07:41:43+00:00

The syzbot-reported stack trace from hell in this discussion thread actually has three nested page faults: https://lore.kernel.org/r/000000000000d5f4fc0616e816d4@google.com ... and I think that's actually the important thing here: - the first page fault is from user space, and triggers the vsyscall emulation. - the second page fault is from __do_sys_gettimeofday(), and that should just have caused the exception that then sets the return value to -EFAULT - the third nested page fault is due to _raw_spin_unlock_irqrestore() -> preempt_schedule() -> trace_sched_switch(), which then causes a BPF trace program to run, which does that bpf_probe_read_compat(), which causes that page fault under pagefault_disable(). It's quite the nasty backtrace, and there's a lot going on. The problem is literally the vsyscall emulation, which sets current->thread.sig_on_uaccess_err = 1; and that causes the fixup_exception() code to send the signal *despite* the exception being caught. And I think that is in fact completely bogus. It's completely bogus exactly because it sends that signal even when it *shouldn't* be sent - like for the BPF user mode trace gathering. In other words, I think the whole "sig_on_uaccess_err" thing is entirely broken, because it makes any nested page-faults do all the wrong things. Now, arguably, I don't think anybody should enable vsyscall emulation any more, but this test case clearly does. I think we should just make the "send SIGSEGV" be something that the vsyscall emulation does on its own, not this broken per-thread state for something that isn't actually per thread. The x86 page fault code actually tried to deal with the "incorrect nesting" by having that: if (in_interrupt()) return; which ignores the sig_on_uaccess_err case when it happens in interrupts, but as shown by this example, these nested page faults do not need to be about interrupts at all. IOW, I think the only right thing is to remove that horrendously broken code. The attached patch looks like the ObviouslyCorrect(tm) thing to do. NOTE! This broken code goes back to this commit in 2011: 4fc3490114bb ("x86-64: Set siginfo and context on vsyscall emulation faults") ... and back then the reason was to get all the siginfo details right. Honestly, I do not for a moment believe that it's worth getting the siginfo details right here, but part of the commit says: This fixes issues with UML when vsyscall=emulate. ... and so my patch to remove this garbage will probably break UML in this situation. I do not believe that anybody should be running with vsyscall=emulate in 2024 in the first place, much less if you are doing things like UML. But let's see if somebody screams. Reported-and-tested-by: syzbot+83e7f982ca045ab4405c@syzkaller.appspotmail.com Signed-off-by: Linus Torvalds Signed-off-by: Ingo Molnar Tested-by: Jiri Olsa Acked-by: Andy Lutomirski Link: https://lore.kernel.org/r/CAHk-=wh9D6f7HUkDgZHKmDCHUQmp+Co89GP+b8+z+G56BKeyNg@mail.gmail.com

x86/cpu/vfm: Add/initialize x86_vfm field to struct cpuinfo_x86

2024-04-22T09:43:48+00:00

Refactor struct cpuinfo_x86 so that the vendor, family, and model fields are overlaid in a union with a 32-bit field that combines all three (together with a one byte reserved field in the upper byte). This will make it easy, cheap, and reliable to check all three values at once. See https://lore.kernel.org/r/Zgr6kT8oULbnmEXx@agluck-desk3 for why the ordering is (low-to-high bits): (vendor, family, model) [ bp: Move comments over the line, add the backstory about the particular order of the fields. ] Signed-off-by: Tony Luck Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/20240416211941.9369-2-tony.luck@intel.com