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Date:      Fri, 2 Mar 2018 00:19:01 +0200
From:      Andriy Gapon <avg@FreeBSD.org>
To:        "Rodney W. Grimes" <freebsd-rwg@pdx.rh.CN85.dnsmgr.net>, Ludovit Koren <ludovit.koren@gmail.com>
Cc:        freebsd-virtualization@freebsd.org
Subject:   Re: bhyve - windows7 installation
Message-ID:  <3ab0c15f-afb5-c880-91d1-ba09a5c8bbc9@FreeBSD.org>
In-Reply-To: <201803011406.w21E62La025815@pdx.rh.CN85.dnsmgr.net>
References:  <86efl3j4y5.fsf@gmail.com> <201803011406.w21E62La025815@pdx.rh.CN85.dnsmgr.net>

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On 01/03/2018 16:06, Rodney W. Grimes wrote:
> Due to the design of the IOMMU you can only manage IO space in page
> (4096 on x86) granually sizes.  The device your trying to pass in
> has a 1024 byte memory region that is part of a 4096 byte page that
> may have other things in it.
> 
> At this time bhyve does not have any way to deal with this, though some
> other hypervisors have techniques that make this work.
> 
> I do not have or know of any list of USB controller cards that
> have 4k aligned and 4k sized BAR's.

I have this local hack for that problem.
It comes without any warranty and its use is completely at your own risk.

commit 74e0a8d1ae01c7aaabd7d965958b735c7cf18871
Author: Andriy Gapon <avg@icyb.net.ua>
Date:   Fri Nov 17 20:17:57 2017 +0200

    bhyve: allow BAR sizes that are not page aligned by rounding them up

    This is based on the assumption that drivers won't access the added space.

diff --git a/usr.sbin/bhyve/pci_passthru.c b/usr.sbin/bhyve/pci_passthru.c
index f314679d912b0..14c1384c6c8f8 100644
--- a/usr.sbin/bhyve/pci_passthru.c
+++ b/usr.sbin/bhyve/pci_passthru.c
@@ -563,13 +563,20 @@ cfginitbar(struct vmctx *ctx, struct passthru_softc *sc)
 		size = bar.pbi_length;

 		if (bartype != PCIBAR_IO) {
-			if (((base | size) & PAGE_MASK) != 0) {
+			if ((base & PAGE_MASK) != 0) {
 				warnx("passthru device %d/%d/%d BAR %d: "
-				    "base %#lx or size %#lx not page aligned\n",
+				    "base %#lx not page aligned\n",
 				    sc->psc_sel.pc_bus, sc->psc_sel.pc_dev,
-				    sc->psc_sel.pc_func, i, base, size);
+				    sc->psc_sel.pc_func, i, base);
 				return (-1);
 			}
+			if ((size & PAGE_MASK) != 0) {
+				warnx("passthru device %d/%d/%d BAR %d: "
+				    "size %#lx not page aligned\n",
+				    sc->psc_sel.pc_bus, sc->psc_sel.pc_dev,
+				    sc->psc_sel.pc_func, i, size);
+				size = round_page(size);
+			}
 		}

 		/* Cache information about the "real" BAR */


-- 
Andriy Gapon



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