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

[Moritz Sanft]

> 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;

Thanks, I tried this on the `-m 67000M` VM and the crash still occurs. I 
extended the previously-added logging to also log the values for `start 
+ size` and `start + PAGE_ALIGN(size)`. Please find the full patch 
including the logging and your change in [1].

The produced logs are as follows:

```
[    0.046472] accept_memory(start=0x00000010db600000 size=0x200000)
[    0.048747]   unaccepted: version=1 unit_size=2097152 
phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
[    0.052557]   (start + size)=0x00000010db800000 (start + 
PAGE_ALIGN(size))=0x00000010db800000
[    0.065217]   bitmap_clear(bitmap=ff1100007d624030, start=32475, len=1)
[    0.067928] accept_memory(start=0x00000010db7ff000 size=0x1000)
[    0.070167]   unaccepted: version=1 unit_size=2097152 
phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
[    0.073917]   (start + size)=0x00000010db800000 (start + 
PAGE_ALIGN(size))=0x00000010db800000
[    0.077150] accept_memory(start=0x00000010db7fe000 size=0x1000)
[    0.079365]   unaccepted: version=1 unit_size=2097152 
phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
[    0.083080]   (start + size)=0x00000010db7ff000 (start + 
PAGE_ALIGN(size))=0x00000010db7ff000
[    0.087123] accept_memory(start=0x00000010db7fd000 size=0x1000)
[    0.089362]   unaccepted: version=1 unit_size=2097152 
phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
[    0.093239]   (start + size)=0x00000010db7fe000 (start + 
PAGE_ALIGN(size))=0x00000010db7fe000
// unrelated
[    0.150522] APIC: Switched APIC routing to: cluster x2apic
[    0.152595] accept_memory(start=0x00000010db7fcf40 size=0x83)
[    0.154745]   unaccepted: version=1 unit_size=2097152 
phys_base=0x100000000 size=0xfdc bitmap=ff1100007d624030
[    0.158479]   (start + size)=0x00000010db7fcfc3 (start + 
PAGE_ALIGN(size))=0x00000010db7fdf40
[    0.161713] BUG: unable to handle page fault for address: 
ff1100007d625008
```

[1]: https://gist.github.com/msanft/d6d7e32a65708f5bd36233649e4facee