6.6-stable review patch. If anyone has any objections, please let me know.
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From: "Kirill A. Shutemov" kirill.shutemov@linux.intel.com
[ upstream commit f4116bfc44621882556bbf70f5284fbf429a5cf6 ]
32-bit emulation was disabled on TDX to prevent a possible attack by a VMM injecting an interrupt on vector 0x80.
Now that int80_emulation() has a check for external interrupts the limitation can be lifted.
To distinguish software interrupts from external ones, int80_emulation() checks the APIC ISR bit relevant to the 0x80 vector. For software interrupts, this bit will be 0.
On TDX, the VAPIC state (including ISR) is protected and cannot be manipulated by the VMM. The ISR bit is set by the microcode flow during the handling of posted interrupts.
[ dhansen: more changelog tweaks ]
Signed-off-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Signed-off-by: Dave Hansen dave.hansen@linux.intel.com Reviewed-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Borislav Petkov (AMD) bp@alien8.de Cc: stable@vger.kernel.org # v6.0+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/coco/tdx/tdx.c | 9 --------- 1 file changed, 9 deletions(-)
--- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -821,14 +821,5 @@ void __init tdx_early_init(void) */ x86_cpuinit.parallel_bringup = false;
- /* - * The VMM is capable of injecting interrupt 0x80 and triggering the - * compatibility syscall path. - * - * By default, the 32-bit emulation is disabled in order to ensure - * the safety of the VM. - */ - ia32_disable(); - pr_info("Guest detected\n"); }