Re: [PATCHv11 11/19] x86/tdx: Convert shared memory back to private on kexec

[Kalra, Ashish]

Hello Boris,

On 5/31/2024 10:14 AM, Borislav Petkov wrote:
> >   static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
> >   {
> > -	if (cc_platform_has(CC_ATTR_MEM_ENCRYPT))
> > -		return __set_memory_enc_pgtable(addr, numpages, enc);
> > +	int ret = 0;
> >   
> > -	return 0;
> > +	if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) {
> > +		if (!down_read_trylock(&mem_enc_lock))
> > +			return -EBUSY;
> > +
> > +		ret = __set_memory_enc_pgtable(addr, numpages, enc);
> > +
> > +		up_read(&mem_enc_lock);
> > +	}
> So CC_ATTR_MEM_ENCRYPT is set for SEV* guests too. You need to change
> that code here to take the lock only on TDX, where you want it, not on
> the others.

SNP guest kexec patches are based on top of this patch-series and SNP 
guests also need this exclusive mem_enc_lock protection, so 
CC_ATTR_MEM_ENCRYPT makes sense to be used here.

Thanks, Ashish