git: f1442847c940 - main - bhyve: passthru: enable BARs before possibly mmap(2)ing them

The branch main has been updated by bz:

URL: https://cgit.FreeBSD.org/src/commit/?id=f1442847c9404d4bc5f5524a0c3362dd39cb14f9

commit f1442847c9404d4bc5f5524a0c3362dd39cb14f9
Author:     Bjoern A. Zeeb <bz@FreeBSD.org>
AuthorDate: 2021-12-23 14:59:49 +0000
Commit:     Bjoern A. Zeeb <bz@FreeBSD.org>
CommitDate: 2021-12-29 17:01:05 +0000

    bhyve: passthru: enable BARs before possibly mmap(2)ing them
    
    The first time we start bhyve with a passthru device everything is fine
    as on boot we do enable BARs.  If a driver (unload) inside bhyve disables
    the BAR(s) as some Linux drivers do, we need to make sure we re-enable
    them on next bhyve start.
    
    If we are trying to mmap a disabled BAR for MSI-X (PCIOCBARMMAP)
    the kernel will give us an EBUSY.
    While we were re-enabling the BAR(s) in the current code loop
    cfginit() was writing the changes out too late to the real hardware.
    
    Move the call to init_msix_table() after the register on the real
    hardware was updated.  That way the kernel will be happy and the
    mmap will succeed and bhyve will start.
    Also simplify the code given the last argument to init_msix_table()
    is unused we do not need to do checks for each bar. [1]
    
    MFC after:      3 days
    PR:             260148
    Pointed out by: markj [1]
    Sponsored by:   The FreeBSD Foundation
    Reviewed by:    markj
    Differential Revision: https://reviews.freebsd.org/D33628
---
 usr.sbin/bhyve/pci_passthru.c | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/usr.sbin/bhyve/pci_passthru.c b/usr.sbin/bhyve/pci_passthru.c
index 9ad19f440e37..769d7c160037 100644
--- a/usr.sbin/bhyve/pci_passthru.c
+++ b/usr.sbin/bhyve/pci_passthru.c
@@ -420,7 +420,7 @@ msix_table_write(struct vmctx *ctx, int vcpu, struct passthru_softc *sc,
 }
 
 static int
-init_msix_table(struct vmctx *ctx, struct passthru_softc *sc, uint64_t base)
+init_msix_table(struct vmctx *ctx, struct passthru_softc *sc)
 {
 	struct pci_devinst *pi = sc->psc_pi;
 	struct pci_bar_mmap pbm;
@@ -548,13 +548,6 @@ cfginitbar(struct vmctx *ctx, struct passthru_softc *sc)
 		sc->psc_bar[i].lobits = lobits;
 		pi->pi_bar[i].lobits = lobits;
 
-		/* The MSI-X table needs special handling */
-		if (i == pci_msix_table_bar(pi)) {
-			error = init_msix_table(ctx, sc, base);
-			if (error) 
-				return (-1);
-		}
-
 		/*
 		 * 64-bit BAR takes up two slots so skip the next one.
 		 */
@@ -596,7 +589,17 @@ cfginit(struct vmctx *ctx, struct pci_devinst *pi, int bus, int slot, int func)
 	write_config(&sc->psc_sel, PCIR_COMMAND, 2,
 	    pci_get_cfgdata16(pi, PCIR_COMMAND));
 
-	error = 0;				/* success */
+	/*
+	 * We need to do this after PCIR_COMMAND got possibly updated, e.g.,
+	 * a BAR was enabled, as otherwise the PCIOCBARMMAP might fail on us.
+	 */
+	error = init_msix_table(ctx, sc);
+	if (error != 0) {
+		warnx("failed to initialize MSI-X table for PCI %d/%d/%d: %d",
+		    bus, slot, func, error);
+		goto done;
+	}
+
 done:
 	return (error);
 }