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x86/virt/tdx: Drop the outdated requirement that TDX be enabled in IRQ context

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Remove TDX's outdated requirement that per-CPU enabling be done via IPI
function call, which was a stale artifact leftover from early versions of
the TDX enablement series.  The requirement that IRQs be disabled should
have been dropped as part of the revamped series that relied on a the KVM
rework to enable VMX at module load.

In other words, the kernel's "requirement" was never a requirement at all,
but instead a reflection of how KVM enabled VMX (via IPI callback) when
the TDX subsystem code was merged.

Note, accessing per-CPU information is safe even without disabling IRQs,
as tdx_online_cpu() is invoked via a cpuhp callback, i.e. from a per-CPU
thread.

Link: https://lore.kernel.org/all/ZyJOiPQnBz31qLZ7@google.com
Tested-by: Chao Gao <chao.gao@intel.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Sagi Shahar <sagis@google.com>
Link: https://patch.msgid.link/20260214012702.2368778-11-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Sean Christopherson 2026-02-13 17:26:56 -08:00
parent 8528a7f9c9
commit 0efe5dc161
2 changed files with 2 additions and 16 deletions
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9
arch/x86/kvm/vmx/tdx.c
View File

@ -3293,17 +3293,10 @@ int tdx_gmem_max_mapping_level(struct kvm *kvm, kvm_pfn_t pfn, bool is_private)
static int tdx_online_cpu(unsigned int cpu)
{
unsigned long flags;
int r;
/* Sanity check CPU is already in post-VMXON */
WARN_ON_ONCE(!(cr4_read_shadow() & X86_CR4_VMXE));
local_irq_save(flags);
r = tdx_cpu_enable();
local_irq_restore(flags);
return r;
return tdx_cpu_enable();
}
static int tdx_offline_cpu(unsigned int cpu)

9
arch/x86/virt/vmx/tdx/tdx.c
View File

@ -106,8 +106,7 @@ static __always_inline int sc_retry_prerr(sc_func_t func,
/*
* Do the module global initialization once and return its result.
* It can be done on any cpu. It's always called with interrupts
* disabled.
* It can be done on any cpu, and from task or IRQ context.
*/
static int try_init_module_global(void)
{
@ -116,8 +115,6 @@ static int try_init_module_global(void)
static bool sysinit_done;
static int sysinit_ret;
lockdep_assert_irqs_disabled();
raw_spin_lock(&sysinit_lock);
if (sysinit_done)
@ -148,8 +145,6 @@ static int try_init_module_global(void)
* global initialization SEAMCALL if not done) on local cpu to make this
* cpu be ready to run any other SEAMCALLs.
*
* Always call this function via IPI function calls.
*
* Return 0 on success, otherwise errors.
*/
int tdx_cpu_enable(void)
@ -160,8 +155,6 @@ int tdx_cpu_enable(void)
if (!boot_cpu_has(X86_FEATURE_TDX_HOST_PLATFORM))
return -ENODEV;
lockdep_assert_irqs_disabled();
if (__this_cpu_read(tdx_lp_initialized))
return 0;