From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- arch/x86/entry/entry.S | 125 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 125 insertions(+) create mode 100644 arch/x86/entry/entry.S (limited to 'arch/x86/entry/entry.S') diff --git a/arch/x86/entry/entry.S b/arch/x86/entry/entry.S new file mode 100644 index 000000000..2bc217bb5 --- /dev/null +++ b/arch/x86/entry/entry.S @@ -0,0 +1,125 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Common place for both 32- and 64-bit entry routines. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "calling.h" + +.pushsection .noinstr.text, "ax" + +/* Clobbers AX, CX, DX */ +SYM_FUNC_START(write_ibpb) + ANNOTATE_NOENDBR + movl $MSR_IA32_PRED_CMD, %ecx + movl _ASM_RIP(x86_pred_cmd), %eax + xorl %edx, %edx + wrmsr + + /* Make sure IBPB clears return stack preductions too. */ + FILL_RETURN_BUFFER %rax, RSB_CLEAR_LOOPS, X86_BUG_IBPB_NO_RET + RET +SYM_FUNC_END(write_ibpb) +EXPORT_SYMBOL_FOR_KVM(write_ibpb); + +SYM_FUNC_START(__WARN_trap) + ANNOTATE_NOENDBR + ANNOTATE_REACHABLE + ud1 (%edx), %_ASM_ARG1 + RET +SYM_FUNC_END(__WARN_trap) +EXPORT_SYMBOL(__WARN_trap) + +.popsection + +/* + * Define the VERW operand that is disguised as entry code so that + * it can be referenced with KPTI enabled. This ensures VERW can be + * used late in exit-to-user path after page tables are switched. + */ +.pushsection .entry.text, "ax" + +.align L1_CACHE_BYTES, 0xcc +SYM_CODE_START_NOALIGN(x86_verw_sel) + UNWIND_HINT_UNDEFINED + ANNOTATE_NOENDBR + .word __KERNEL_DS +.align L1_CACHE_BYTES, 0xcc +SYM_CODE_END(x86_verw_sel); +EXPORT_SYMBOL_FOR_KVM(x86_verw_sel); + +.popsection + +THUNK warn_thunk_thunk, __warn_thunk + +/* + * Clang's implementation of TLS stack cookies requires the variable in + * question to be a TLS variable. If the variable happens to be defined as an + * ordinary variable with external linkage in the same compilation unit (which + * amounts to the whole of vmlinux with LTO enabled), Clang will drop the + * segment register prefix from the references, resulting in broken code. Work + * around this by avoiding the symbol used in -mstack-protector-guard-symbol= + * entirely in the C code, and use an alias emitted by the linker script + * instead. + */ +#if defined(CONFIG_STACKPROTECTOR) && defined(CONFIG_SMP) +EXPORT_SYMBOL(__ref_stack_chk_guard); +#endif + +#if IS_ENABLED(CONFIG_KVM_INTEL) +.macro IDT_DO_EVENT_IRQOFF call_insn call_target + /* + * Unconditionally create a stack frame, getting the correct RSP on the + * stack (for x86-64) would take two instructions anyways, and RBP can + * be used to restore RSP to make objtool happy (see below). + */ + push %_ASM_BP + mov %_ASM_SP, %_ASM_BP + +#ifdef CONFIG_X86_64 + /* + * Align RSP to a 16-byte boundary (to emulate CPU behavior) before + * creating the synthetic interrupt stack frame for the IRQ/NMI. + */ + and $-16, %rsp + push $__KERNEL_DS + push %rbp +#endif + pushf + push $__KERNEL_CS + \call_insn \call_target + + /* + * "Restore" RSP from RBP, even though IRET has already unwound RSP to + * the correct value. objtool doesn't know the callee will IRET and, + * without the explicit restore, thinks the stack is getting walloped. + * Using an unwind hint is problematic due to x86-64's dynamic alignment. + */ + leave + RET +.endm + +#ifndef CONFIG_X86_64 +.pushsection .text, "ax" +SYM_FUNC_START(idt_do_interrupt_irqoff) + IDT_DO_EVENT_IRQOFF CALL_NOSPEC _ASM_ARG1 +SYM_FUNC_END(idt_do_interrupt_irqoff) +.popsection +#endif + +.pushsection .noinstr.text, "ax" +SYM_FUNC_START(idt_do_nmi_irqoff) + IDT_DO_EVENT_IRQOFF call asm_exc_nmi_kvm_vmx +SYM_FUNC_END(idt_do_nmi_irqoff) +.popsection +#endif -- cgit v1.3.1