linux-kernel - Re: [PATCH 21/25] KVM: x86: Introduce KVM_TDX_GET

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <Ztaq7YKVHSwfAzvJ@tlindgre-MOBL1>
Date: Tue, 3 Sep 2024 09:21:33 +0300
From: Tony Lindgren <tony.lindgren@...ux.intel.com>
To: Tao Su <tao1.su@...ux.intel.com>
Cc: Rick Edgecombe <rick.p.edgecombe@...el.com>, seanjc@...gle.com,
	pbonzini@...hat.com, kvm@...r.kernel.org, kai.huang@...el.com,
	isaku.yamahata@...il.com, xiaoyao.li@...el.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 21/25] KVM: x86: Introduce KVM_TDX_GET_CPUID

On Mon, Aug 19, 2024 at 10:59:49AM +0800, Tao Su wrote:
> On Mon, Aug 12, 2024 at 03:48:16PM -0700, Rick Edgecombe wrote:
> > From: Xiaoyao Li <xiaoyao.li@...el.com>
> > +		/*
> > +		 * Work around missing support on old TDX modules, fetch
> > +		 * guest maxpa from gfn_direct_bits.
> > +		 */
> > +		if (output_e->function == 0x80000008) {
> > +			gpa_t gpa_bits = gfn_to_gpa(kvm_gfn_direct_bits(vcpu->kvm));
> > +			unsigned int g_maxpa = __ffs(gpa_bits) + 1;
> > +
> > +			output_e->eax &= ~0x00ff0000;
> > +			output_e->eax |= g_maxpa << 16;
> > +		}
> 
> I suggest putting all guest_phys_bits related WA in a WA-only patch, which will
> be clearer.

The 80000008 workaround needs to be tidied up for sure, it's hard to follow.

> > --- a/arch/x86/kvm/vmx/tdx.h
> > +++ b/arch/x86/kvm/vmx/tdx.h
> > @@ -25,6 +25,11 @@ struct kvm_tdx {
> >  	bool finalized;
> >  
> >  	u64 tsc_offset;
> > +
> > +	/* For KVM_MAP_MEMORY and KVM_TDX_INIT_MEM_REGION. */
> > +	atomic64_t nr_premapped;
> 
> I don't see it is used in this patch set.

Yes that should have been in a later patch.

Regards,

Tony