Re: [BUG] Fault during memory acceptance for TDX VMs with certain memory sizes

[Kiryl Shutsemau <kas@kernel.org>]

On Fri, Feb 13, 2026 at 09:34:46AM +0100, Moritz Sanft wrote:
> > Any chance you can throw
> > a bunch of printk()'s in the kernel and see what all the fields in here are:
> > 
> > struct efi_unaccepted_memory {
> >         u32 version;
> >         u32 unit_size;
> >         u64 phys_base;
> >         u64 size;
> >         unsigned long bitmap[];
> > };
> > 
> > Along with the address of bitmap[] and all the calls to: bitmap_clear()?
> 
> Thanks for the guidance. I've added this logging via the patch in [1], which
> produced the following output:
> 
> ```
> [    0.033292] accept_memory(start=0x0000000000099000 size=0x6000)
> [    0.037860]   unaccepted: version=1 unit_size=2097152
> phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
> [    0.041469] Using GB pages for direct mapping
> [    0.043090] accept_memory(start=0x00000010db600000 size=0x200000)
> [    0.045311]   unaccepted: version=1 unit_size=2097152
> phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
> [    0.058123]   bitmap_clear(bitmap=ff1100007d624030, start=32475, len=1)
> [    0.060921] accept_memory(start=0x00000010db7ff000 size=0x1000)
> [    0.063142]   unaccepted: version=1 unit_size=2097152
> phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
> [    0.066865] accept_memory(start=0x00000010db7fe000 size=0x1000)
> [    0.069096]   unaccepted: version=1 unit_size=2097152
> phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
> [    0.073705] accept_memory(start=0x00000010db7fd000 size=0x1000)
> [    0.075908]   unaccepted: version=1 unit_size=2097152
> phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
> // unrelated logs omitted here
> [    0.134988] accept_memory(start=0x00000010db7fcf40 size=0x83)
> [    0.137152]   unaccepted: version=1 unit_size=2097152
> phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
> [    0.140828] BUG: unable to handle page fault for address:
> ff1100007d625008
> ```
> 
> Find a full log attached in [2].
> 
> Please let me know if we need to gather any further logs - we're happy to do
> so.

Could you check it this patch makes a difference:

diff --git a/drivers/firmware/efi/unaccepted_memory.c b/drivers/firmware/efi/unaccepted_memory.c
index c2c067eff634..f2a00cd429f2 100644
--- a/drivers/firmware/efi/unaccepted_memory.c
+++ b/drivers/firmware/efi/unaccepted_memory.c
@@ -35,7 +35,7 @@ void accept_memory(phys_addr_t start, unsigned long size)
 	struct efi_unaccepted_memory *unaccepted;
 	unsigned long range_start, range_end;
 	struct accept_range range, *entry;
-	phys_addr_t end = start + size;
+	phys_addr_t end = start + PAGE_ALIGN(size);
 	unsigned long flags;
 	u64 unit_size;
 
-- 
  Kiryl Shutsemau / Kirill A. Shutemov