On Thu, Aug 14, 2025, Kai Huang wrote:
> arch/x86/include/asm/tdx.h | 2 ++
> arch/x86/kvm/vmx/tdx.c | 12 ++++++++++++
> arch/x86/virt/vmx/tdx/tdx.c | 12 ++++++++++++
> 3 files changed, 26 insertions(+)
>
> diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
> index 0922265c6bdc..e9a213582f03 100644
> --- a/arch/x86/include/asm/tdx.h
> +++ b/arch/x86/include/asm/tdx.h
> @@ -217,6 +217,7 @@ u64 tdh_mem_page_remove(struct tdx_td *td, u64 gpa, u64 level, u64 *ext_err1, u6
> u64 tdh_phymem_cache_wb(bool resume);
> u64 tdh_phymem_page_wbinvd_tdr(struct tdx_td *td);
> u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page);
> +void tdx_cpu_flush_cache(void);
> #else
> static inline void tdx_init(void) { }
> static inline int tdx_cpu_enable(void) { return -ENODEV; }
> @@ -224,6 +225,7 @@ static inline int tdx_enable(void) { return -ENODEV; }
> static inline u32 tdx_get_nr_guest_keyids(void) { return 0; }
> static inline const char *tdx_dump_mce_info(struct mce *m) { return NULL; }
> static inline const struct tdx_sys_info *tdx_get_sysinfo(void) { return NULL; }
> +static inline void tdx_cpu_flush_cache(void) { }
Stub is unnecessary. tdx.c is built iff KVM_INTEL_TDX=y, and that depends on
INTEL_TDX_HOST.
At a glance, some of the existing stubs are useless as well.
> #endif /* CONFIG_INTEL_TDX_HOST */
>
> #endif /* !__ASSEMBLER__ */
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 66744f5768c8..1bc6f52e0cd7 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -442,6 +442,18 @@ void tdx_disable_virtualization_cpu(void)
> tdx_flush_vp(&arg);
> }
> local_irq_restore(flags);
> +
> + /*
> + * No more TDX activity on this CPU from here. Flush cache to
> + * avoid having to do WBINVD in stop_this_cpu() during kexec.
> + *
> + * Kexec calls native_stop_other_cpus() to stop remote CPUs
> + * before booting to new kernel, but that code has a "race"
> + * when the normal REBOOT IPI times out and NMIs are sent to
> + * remote CPUs to stop them. Doing WBINVD in stop_this_cpu()
> + * could potentially increase the possibility of the "race".
> + */
> + tdx_cpu_flush_cache();
IIUC, this can be:
if (IS_ENABLED(CONFIG_KEXEC))
tdx_cpu_flush_cache();
> }
>
> #define TDX_SEAMCALL_RETRIES 10000
> diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c
> index 3ea6f587c81a..c26e2e07ff6b 100644
> --- a/arch/x86/virt/vmx/tdx/tdx.c
> +++ b/arch/x86/virt/vmx/tdx/tdx.c
> @@ -1870,3 +1870,15 @@ u64 tdh_phymem_page_wbinvd_hkid(u64 hkid, struct page *page)
> return seamcall(TDH_PHYMEM_PAGE_WBINVD, &args);
> }
> EXPORT_SYMBOL_GPL(tdh_phymem_page_wbinvd_hkid);
> +
> +void tdx_cpu_flush_cache(void)
> +{
> + lockdep_assert_preemption_disabled();
> +
> + if (!this_cpu_read(cache_state_incoherent))
> + return;
> +
> + wbinvd();
> + this_cpu_write(cache_state_incoherent, false);
> +}
> +EXPORT_SYMBOL_GPL(tdx_cpu_flush_cache);
> --
> 2.50.1
>
