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CC:     "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Tianyu Lan <Tianyu.Lan@microsoft.com>
Subject: RE: [PATCH v4 5/6] Drivers: hv: vmbus: Support TDX guests
Thread-Topic: [PATCH v4 5/6] Drivers: hv: vmbus: Support TDX guests
Thread-Index: AQHZaluiU1mCuu/uekyGswn5O4Hjua8nuTuQgA109FA=
Date:   Fri, 21 Apr 2023 03:34:35 +0000
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> From: Michael Kelley (LINUX) <mikelley@microsoft.com>
> Sent: Wednesday, April 12, 2023 7:05 AM
> > @@ -168,6 +170,30 @@ int hv_synic_alloc(void)
> >  			pr_err("Unable to allocate post msg page\n");
> >  			goto err;
> >  		}
> > +
> > +
> > +		if (hv_isolation_type_tdx()) {
> > +			ret =3D set_memory_decrypted(
> > +				(unsigned long)hv_cpu->synic_message_page, 1);
> > +			if (ret) {
> > +				pr_err("Failed to decrypt SYNIC msg page\n");
> > +				goto err;
> > +			}
> > +
> > +			ret =3D set_memory_decrypted(
> > +				(unsigned long)hv_cpu->synic_event_page, 1);
> > +			if (ret) {
> > +				pr_err("Failed to decrypt SYNIC event page\n");
> > +				goto err;
> > +			}
> > +
> > +			ret =3D set_memory_decrypted(
> > +				(unsigned long)hv_cpu->post_msg_page, 1);
> > +			if (ret) {
> > +				pr_err("Failed to decrypt post msg page\n");
> > +				goto err;
> > +			}
> > +		}
>=20
> One other comment:  The memory for the synic_message_page,
> synic_event_page, and post_msg_page is obtained using get_zeroed_page().
> But after the decryption, the memory contents will be random garbage that

I'm not sure about this, as I don't see any "unknown msgtype=3D" message fr=
om
vmbus_on_msg_dpc() :-)=20

I agree it's good to add a memset(). Will do it in v5.

> isn't all zeroes.  You'll need to do a memset() after the decryption to g=
et the
> contents back to zero.  Compare with Patch 6 in Tianyu's fully enlightene=
d
> SNP patch series.
>=20
> Michael
=20