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Mon, 29 Jun 2020 11:57:43 +0200 MIME-Version: 1.0 Message-ID: From: joshua_peter@web.de To: =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= Subject: Aw: Re: Questions about PVH memory layout Content-Type: text/plain; charset=UTF-8 Date: Mon, 29 Jun 2020 11:57:43 +0200 Importance: normal Sensitivity: Normal In-Reply-To: <20200629085758.GE735@Air-de-Roger> References: <20200629085758.GE735@Air-de-Roger> Content-Transfer-Encoding: quoted-printable X-UI-Message-Type: mail X-Priority: 3 X-Provags-ID: V03:K1:wHaBkn4x47uyB+TSXlHaBfdcH/o41086w8iOhSpoxSLCqkO4FmqrVWeu4IOQFfeI1q1x/ XDxppZ6R+2uitgMnkJJUZClhlHpVH9ZMoDjHjC7LzDw42Zm4aKaAtB5WoSPCkvQaVfVjkqX5r3WQ 5vIVxW0Xk61ScduwA55/i/+9s+FIVhjtM2G20NX/fAclPsNyDurEj4UcnAl9nuq0lI0Aqu7EBsm6 +favt9GJfwlcx0n5uMx4LbQBdjALJr0sHbOLUD/2+PjZ/bV7E/RG25EjLRBeyHQfE6KSlD4NLxQR ZI= X-UI-Out-Filterresults: notjunk:1;V03:K0:SLQln+3Toao=:2rlSCgt25VFEwEDSPIr4VC 6a6cBrYNz86IpCofQpsIThgzVsDrwNOAoPv2hFtlWevm7W0BmPBNCuS8fDjKUhMsxLPWhEeBV KqSNegLGG4K0ih0wAU6zfgTsIuNuYBh4fzQBHM3FN7apRXOwECrAy8AfHYAN4EAqqZ+xc4dPU 2evCJLAUGHBDY1TOENWP6UA3d4t12rjch6rx8aqwlz2PWrM3np3zE8fXLLETamhYtWeC4lKCl E8jGZ6ZQ1pm42aEYvvOl+oUabml52kTQX7LCwR9uwWRAzFKGGbnEiV3Oe6+QClRcKCFIm+eIp WjoPbxxDump0JbKG++avMF+MTzpZbCO7MTZgJ54EHIVKMuv9zJovtNaFKCLHXUvvOk30EIx/7 6YCBHASj/Y6uUzlZPpXyo9DCnQgHqXjNOmvBYkdWlC/kyuKVSgFhV84TPt5M7f9/9nlmprTTZ pSzGe1D681V1c9UyYCEsOuhEoNROsPAe0dEGw/0N1tH5pRZNIpwqln37eE7JcHAeo25UK+M3J SSBNvfZJUFgCzK7AGawvIhgOX+7geXw2m3UjPQ+ozVfVEGqMR/8FTLwxDBHaYdidcuMGQRfnj 4wcI6D2OQwhso2u4rkXId+iHollGgLUIkQE7/DL0vDNC1J2/Qw9Pye0ZX3/9U0se4mIFo4/hM 6QoDY0O4RyjPC3oadmCKj1RpGCjpDRlskosGuBjkbhQCXU2AR0d1fPfNkR/xaJ5AKugo= X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: xen-devel@lists.xenproject.org Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Hi Roger, thank you very much for your help=2E Further replies are inline=2E > Gesendet: Montag, 29=2E Juni 2020 um 10:57 Uhr > Von: "Roger Pau Monn=C3=A9" > An: joshua_peter@web=2Ede > Cc: xen-devel@lists=2Exenproject=2Eorg > Betreff: Re: Questions about PVH memory layout > > > The other > > thing is, the first 512 pages at the beginning of the address space ar= e > > mapped linearly, which usually leads to them being mapped as a single > > 2MB pages=2E But there is this one page at 0x00001000 that sticks out > > completely=2E By that I mean (to make things more concrete), in my PVH > > guest the page at 0x00000000 maps to 0x13C200000, 0x00002000 maps to > > 0x13C202000, 0x00003000 maps to 0x13C203000, etc=2E But 0x00001000 map= s > > to 0xB8DBD000, which seems very odd to me (at least from simply lookin= g > > at the addresses)=2E >=20 > Are you booting some OS on the guest before dumping the memory map? > Keep in mind guest have the ability to modify the physmap, either by > mapping Xen shared areas (like the shared info page) or just by using > ballooning in order to poke holes into it (which can be populated > later)=2E It's either that or some kind of bug/missoptimization in > meminit_hvm (also part of tools/libxc/xc_dom_x86=2Ec)=2E Yes, my bad=2E I'm booting into Arch Linux=2E This must have been lost whi= le I was editing my e-mail=2E > Can you check if this 'weird' mapping at 0x1000 is also present if you > boot the guest with 'xl create -p foo=2Ecfg'? (that will prevent the > guests from running, so that you can get the memory map before the > guest has modified it in any way)=2E Yeah, starting with the "-p" flag does get rid of this 'weird' mapping=2E Thank you again=2E This cleared up a bunch of things=2E Best regards, Peter