Date: Sun, 30 Oct 2016 17:32:43 +0100 From: Harry Schmalzbauer <freebsd@omnilan.de> To: freebsd-stable@freebsd.org Cc: Alexander Motin <mav@freebsd.org> Subject: bhyve(8) passthru affects ahci-hd with device backend [Was: Re: Unexpected ahci-hd bytes when running in bhyve(8)] Message-ID: <581620AB.3050203@omnilan.de> In-Reply-To: <5814DDDC.60104@omnilan.de> References: <58124200.5080306@omnilan.de> <5814C101.90805@omnilan.de> <5814DDDC.60104@omnilan.de>
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Bez=C3=BCglich Harry Schmalzbauer's Nachricht vom 29.10.2016 19:35 (loca= ltime): > Bez=C3=BCglich Harry Schmalzbauer's Nachricht vom 29.10.2016 17:32 (lo= caltime): > > =E2=80=A6 >> Like mentioned, while reading the first 448 bytes on the host, I get >> identical results from /usr/local/guest.img and /dev/ada4, but when >> attaching /dev/ada4 to ahci-hd (-s 7,ahci-hd,/dev/ada4) and inspecting= >> inside vmm, all I see is 0x0, while ahci-hd attached >> /usr/local/guest.img shows the same pmbr as on the host!? >> >> Do I have to exclude /dev/ada4 on the host from geom? As soon as bhyve= >> opens /dev/ada4, all partitions vanish from the host =E2=80=93 probabl= y ada4 >> itself gets blocked somehow? =E2=80=A6 > Just another symptom I can only describe, not debug: > Opening /dev/adaX on the host works by 'hd /dev/ada4 | less', > but not inside the guest, where it just leads to endless IO when trying= > the same on the ahci-hd attached /dev/ada4 The described defects only happen when passthru is used with bhyve(8)!!! If I simply don't attach the passthru-device (keeping memory wired), everything works the way it's supposed to do. Opening the guest-ada1-device with hexdump works, geom tastes GPT and the first 448 bytes show exactly the pMBR like on the host. As soon as I start the guest with the passthru device (doesn't matter which slot, tested with a 82574L), the ahci-hd can't be read nymore, just returning 0x0 when dumped. Shall I file a bug report? Anybody aware of that or any idea where to start fixing? To summarize: FreeBSD-11-RELEASE hosting a bhyve(8) guest with a physical device as storage backend (regardless if accessed through virtio-blk or ahci-hd) corrupts guest-disk access if there's also a passthrough device attached.= If you use a file-backed ahci-hd (or virtio-blk) device, the problem doesn't show up, regardelss if there's passthru involved or not. Thanks, -Harry
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