svn commit: r366771 - head/usr.sbin/bhyve

[Ryan Moeller]

Author: freqlabs
Date: Fri Oct 16 20:27:20 2020
New Revision: 366771
URL: https://svnweb.freebsd.org/changeset/base/366771

Log:
  bhyve: Update TX descriptor base address and host mapping on change
  
  bhyve sometimes segfaults when using an e1000 NIC with a Windows guest.
  
  We are only updating our tdba and cached host mapping when the low address
  register is written and when tx is set enabled, but not when the high address
  or length registers are written. It is observed that Windows 10 is occasionally
  enabling tx first then writing the registers in the order low, high, len. This
  leaves us with a bogus base address and mapping, which causes a segfault later
  when we try to copy from a descriptor that has unpredictable garbage in a
  pointer.
  
  Updating the address and mapping when any of those registers change seems to fix
  that particular issue.
  
  Reviewed by:	mav, grehan (bhyve)
  MFC after:	1 week
  Sponsored by:	iXsystems, Inc.
  Differential Revision:	https://reviews.freebsd.org/D26798

Modified:
  head/usr.sbin/bhyve/pci_e82545.c

Modified: head/usr.sbin/bhyve/pci_e82545.c
==============================================================================
--- head/usr.sbin/bhyve/pci_e82545.c	Fri Oct 16 17:51:09 2020	(r366770)
+++ head/usr.sbin/bhyve/pci_e82545.c	Fri Oct 16 20:27:20 2020	(r366771)
@@ -1701,18 +1701,18 @@ e82545_write_register(struct e82545_softc *sc, uint32_
 		break;
 	case E1000_TDBAL(0):
 		sc->esc_TDBAL = value & ~0xF;
-		if (sc->esc_tx_enabled) {
-			/* Apparently legal */
+		if (sc->esc_tx_enabled)
 			e82545_tx_update_tdba(sc);
-		}
 		break;
 	case E1000_TDBAH(0):
-		//assert(!sc->esc_tx_enabled);		
 		sc->esc_TDBAH = value;
+		if (sc->esc_tx_enabled)
+			e82545_tx_update_tdba(sc);
 		break;
 	case E1000_TDLEN(0):
-		//assert(!sc->esc_tx_enabled);
 		sc->esc_TDLEN = value & ~0xFFF0007F;
+		if (sc->esc_tx_enabled)
+			e82545_tx_update_tdba(sc);
 		break;
 	case E1000_TDH(0):
 		//assert(!sc->esc_tx_enabled);