On Tue, Jan 30, 2024 at 07:04:00PM +0100, Paolo Bonzini wrote:
MKTME repurposes the high bit of physical address to key id for encryption key and, even though MAXPHYADDR in CPUID[0x80000008] remains the same, the valid bits in the MTRR mask register are based on the reduced number of physical address bits.
detect_tme() in arch/x86/kernel/cpu/intel.c detects TME and subtracts it from the total usable physical bits, but it is called too late. Move the call to early_init_intel() so that it is called in setup_arch(), before MTRRs are setup.
This fixes boot on some TDX-enabled systems which until now only worked with "disable_mtrr_cleanup". Without the patch, the values written to the MTRRs mask registers were 52-bit wide (e.g. 0x000fffff_80000800) and the writes failed; with the patch, the values are 46-bit wide, which matches the reduced MAXPHYADDR that is shown in /proc/cpuinfo.
Fixes: cb06d8e3d020 ("x86/tme: Detect if TME and MKTME is activated by BIOS", 2018-03-12) Reported-by: Zixi Chen zixchen@redhat.com Cc: Kirill A. Shutemov kirill.shutemov@linux.intel.com Cc: Xiaoyao Li xiaoyao.li@intel.com Cc: Kai Huang kai.huang@linux.intel.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Ingo Molnar mingo@kernel.org Cc: x86@kernel.org Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini pbonzini@redhat.com
I've seen the patch before, although by different author and with different commit message, not sure what is going on.
I had concern about that patch and I don't think it was addressed. See the thread:
https://lore.kernel.org/all/20231002224752.33qa2lq7q2w4nqws@box