Re: [PATCH 6.6.y] x86/tdx: Fix arch_safe_halt() execution for TDX VMs

[Sasha Levin <sashal@kernel.org>]

[ Sasha's backport helper bot ]

Hi,

Summary of potential issues:
⚠️ Found matching upstream commit but patch is missing proper reference to it

Found matching upstream commit: 9f98a4f4e7216dbe366010b4cdcab6b220f229c4

Status in newer kernel trees:
6.14.y | Present (different SHA1: 8defd0d8678b)
6.13.y | Present (different SHA1: f88759f8f742)
6.12.y | Present (different SHA1: 7aff5ffe2c87)

Note: The patch differs from the upstream commit:
---
1:  9f98a4f4e7216 ! 1:  882c95e29bbba x86/tdx: Fix arch_safe_halt() execution for TDX VMs
    @@ Commit message
         Cc: Josh Poimboeuf <jpoimboe@redhat.com>
         Cc: stable@vger.kernel.org
         Link: https://lore.kernel.org/r/20250228014416.3925664-3-vannapurve@google.com
    +    (cherry picked from commit 9f98a4f4e7216dbe366010b4cdcab6b220f229c4)
     
      ## arch/x86/Kconfig ##
     @@ arch/x86/Kconfig: config INTEL_TDX_GUEST
    @@ arch/x86/coco/tdx/tdx.c
      #include <asm/insn-eval.h>
     +#include <asm/paravirt_types.h>
      #include <asm/pgtable.h>
    - #include <asm/set_memory.h>
      #include <asm/traps.h>
    + 
     @@ arch/x86/coco/tdx/tdx.c: static int handle_halt(struct ve_info *ve)
      	return ve_instr_len(ve);
      }
    @@ arch/x86/coco/tdx/tdx.c: void __cpuidle tdx_safe_halt(void)
     +
      static int read_msr(struct pt_regs *regs, struct ve_info *ve)
      {
    - 	struct tdx_module_args args = {
    + 	struct tdx_hypercall_args args = {
     @@ arch/x86/coco/tdx/tdx.c: void __init tdx_early_init(void)
    - 	x86_platform.guest.enc_kexec_begin	     = tdx_kexec_begin;
    - 	x86_platform.guest.enc_kexec_finish	     = tdx_kexec_finish;
    + 	x86_platform.guest.enc_cache_flush_required  = tdx_cache_flush_required;
    + 	x86_platform.guest.enc_tlb_flush_required    = tdx_tlb_flush_required;
      
     +	/*
     +	 * Avoid "sti;hlt" execution in TDX guests as HLT induces a #VE that
    @@ arch/x86/include/asm/tdx.h: void tdx_get_ve_info(struct ve_info *ve);
      
      bool tdx_early_handle_ve(struct pt_regs *regs);
      
    -@@ arch/x86/include/asm/tdx.h: void __init tdx_dump_td_ctls(u64 td_ctls);
    +@@ arch/x86/include/asm/tdx.h: int tdx_mcall_get_report0(u8 *reportdata, u8 *tdreport);
      #else
      
      static inline void tdx_early_init(void) { };
    @@ arch/x86/include/asm/tdx.h: void __init tdx_dump_td_ctls(u64 td_ctls);
      
     
      ## arch/x86/kernel/process.c ##
    -@@ arch/x86/kernel/process.c: void __init select_idle_routine(void)
    +@@ arch/x86/kernel/process.c: void select_idle_routine(const struct cpuinfo_x86 *c)
      		static_call_update(x86_idle, mwait_idle);
      	} else if (cpu_feature_enabled(X86_FEATURE_TDX_GUEST)) {
      		pr_info("using TDX aware idle routine\n");
     -		static_call_update(x86_idle, tdx_safe_halt);
     +		static_call_update(x86_idle, tdx_halt);
    - 	} else {
    + 	} else
      		static_call_update(x86_idle, default_idle);
    - 	}
    + }
---

Results of testing on various branches:

| Branch                    | Patch Apply | Build Test |
|---------------------------|-------------|------------|
| stable/linux-6.6.y        |  Success    |  Success   |