From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: mx.groups.io; dkim=missing; spf=pass (domain: redhat.com, ip: 209.132.183.28, mailfrom: imammedo@redhat.com) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by groups.io with SMTP; Thu, 05 Sep 2019 08:45:08 -0700 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C49561056FB1; Thu, 5 Sep 2019 15:45:07 +0000 (UTC) Received: from localhost (unknown [10.43.2.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id 143DA60C63; Thu, 5 Sep 2019 15:45:04 +0000 (UTC) Date: Thu, 5 Sep 2019 17:45:03 +0200 From: "Igor Mammedov" To: Laszlo Ersek Cc: "Chen, Yingwen" , "devel@edk2.groups.io" , Phillip Goerl , qemu devel list , Alex Williamson , "Yao, Jiewen" , "Nakajima, Jun" , "Kinney, Michael D" , Paolo Bonzini , Boris Ostrovsky , "rfc@edk2.groups.io" , Joao Marcal Lemos Martins Subject: Re: [Qemu-devel] [edk2-rfc] [edk2-devel] CPU hotplug using SMM with QEMU+OVMF Message-ID: <20190905174503.2acaa46a@redhat.com> In-Reply-To: References: <8091f6e8-b1ec-f017-1430-00b0255729f4@redhat.com> <7f2d2f1e-2dd8-6914-c55e-61067e06b142@redhat.com> <3661c0c5-3da4-1453-a66a-3e4d4022e876@redhat.com> <74D8A39837DF1E4DA445A8C0B3885C503F76FDAF@shsmsx102.ccr.corp.intel.com> <74D8A39837DF1E4DA445A8C0B3885C503F7728AB@shsmsx102.ccr.corp.intel.com> <20190827203102.56d0d048@redhat.com> <033ced1a-1399-968e-cce6-6b15a20b0baf@redhat.com> <20190830164802.1b17ff26@redhat.com> <20190902104534.46e58c95@redhat.com> <2ef1910e-8879-028a-4db6-97a0ecc64083@redhat.com> <20190903165355.27e1eee0@redhat.com> <17985043-f16c-0ff4-6f60-b6762d72e848@redhat.com> <20190904115207.76bc6bfe@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.6.2 (mx1.redhat.com [10.5.110.64]); Thu, 05 Sep 2019 15:45:07 +0000 (UTC) Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 5 Sep 2019 15:08:31 +0200 Laszlo Ersek wrote: > On 09/04/19 11:52, Igor Mammedov wrote: > > > it could be stolen RAM + black hole like TSEG, assuming fw can live without RAM(0x30000+128K) range > > (in this case fwcfg interface would only work for locking down the range) > > > > or > > > > we can actually have a dedicated SMRAM (like in my earlier RFC), > > in this case FW can use RAM(0x30000+128K) when SMRAM isn't mapped into RAM address space > > (in this case fwcfg would be used to temporarily map SMRAM into normal RAM and unmap/lock > > after SMI relocation handler was initialized). > > > > If possible I'd prefer a simpler TSEG like variant. > > I think TSEG-like behavior is between these two. That is, I believe we > should have explicit open/close/lock operations. And, when the range is > closed (meaning, closed+unlocked, or closed+locked), then the black hole > should take effect for code that's not running in SMM. > > Put differently, its like the second choice, except the range never > appears as normal RAM. "When SMRAM isn't mapped into RAM address space", > then the address range shows "nothing" (black hole). I guess we at point where patch is better then words, I'll send one as reply here shortly. I've just implemented subset of above (opened, closed+locked). > Regarding "fw can live without RAM(0x30000+128K) range" -- do you mean > whether the firmware could use another RAM area for fw_cfg DMA? > > If that's the question, then I wouldn't worry about it. I'd remove the > 0x30000+128K range from the memory map, so the fw_cfg stuff (or anything > else) would never allocate memory from the range. It's much more > concerning to me however how the SMM infrastructure would deal with a > hole in the memory map right there. I didn't mean fwcfg in this context, what I meant if firmware were able to avoid using RAM(0x30000+128K) range (since it becomes unusable after locking). Looks like you just answered it here