git: 5775540d36dd - stable/13 - bhyve: add more slop to 64 bit BARs

The branch stable/13 has been updated by manu:

URL: https://cgit.FreeBSD.org/src/commit/?id=5775540d36ddb7d4d5d0cd26d2365ca84060aec5

commit 5775540d36ddb7d4d5d0cd26d2365ca84060aec5
Author:     Corvin Köhne <CorvinK@beckhoff.com>
AuthorDate: 2022-01-03 13:19:39 +0000
Commit:     Emmanuel Vadot <manu@FreeBSD.org>
CommitDate: 2022-01-17 12:53:22 +0000

    bhyve: add more slop to 64 bit BARs
    
    Bhyve allocates small 64 bit BARs below 4 GB and generates ACPI tables
    based on this allocation. If the guest decides to relocate those BARs
    above 4 GB, it could lead to mismatching ACPI tables. Especially
    when using OVMF with enabled bus enumeration it could cause
    issues. OVMF relocates all 64 bit BARs above 4 GB. The guest OS
    may be unable to recover from this situation and disables some PCI
    devices because their BARs are located outside of the MMIO space
    reported by ACPI. Avoid this situation by giving the guest more
    space for relocating BARs.
    
    Let's be paranoid. The available space for BARs below 4 GB is 512 MB
    large. Use a slop of 512 MB. It'll allow the guest to relocate all
    BARs below 4 GB to an address above 4 GB. We could run into issues
    when we exceeding the memlimit above 4 GB. However, this space has
    a size of 32 GB. Even when using many PCI device with large BARs
    like framebuffer or when using multiple PCI busses, it's very
    unlikely that we run out of space due to the large slop.
    Additionally, this situation will occur on startup and not at runtime
    which is much better.
    
    Reviewed by:    markj
    MFC after:      2 weeks
    Sponsored by:   Beckhoff Automation GmbH & Co. KG
    Differential Revision:  https://reviews.freebsd.org/D33118
    
    (cherry picked from commit 7d55d295086e0f568b42c89604fad3e47633b2ed)
---
 usr.sbin/bhyve/pci_emul.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/usr.sbin/bhyve/pci_emul.c b/usr.sbin/bhyve/pci_emul.c
index 4365cda234b3..e9c88922b0ef 100644
--- a/usr.sbin/bhyve/pci_emul.c
+++ b/usr.sbin/bhyve/pci_emul.c
@@ -1218,7 +1218,8 @@ pci_ecfg_base(void)
 }
 
 #define	BUSIO_ROUNDUP		32
-#define	BUSMEM_ROUNDUP		(1024 * 1024)
+#define	BUSMEM32_ROUNDUP	(1024 * 1024)
+#define	BUSMEM64_ROUNDUP	(512 * 1024 * 1024)
 
 int
 init_pci(struct vmctx *ctx)
@@ -1320,14 +1321,14 @@ init_pci(struct vmctx *ctx)
 		pci_emul_iobase = roundup2(pci_emul_iobase, BUSIO_ROUNDUP);
 		bi->iolimit = pci_emul_iobase;
 
-		pci_emul_membase32 += BUSMEM_ROUNDUP;
+		pci_emul_membase32 += BUSMEM32_ROUNDUP;
 		pci_emul_membase32 = roundup2(pci_emul_membase32,
-		    BUSMEM_ROUNDUP);
+		    BUSMEM32_ROUNDUP);
 		bi->memlimit32 = pci_emul_membase32;
 
-		pci_emul_membase64 += BUSMEM_ROUNDUP;
+		pci_emul_membase64 += BUSMEM64_ROUNDUP;
 		pci_emul_membase64 = roundup2(pci_emul_membase64,
-		    BUSMEM_ROUNDUP);
+		    BUSMEM64_ROUNDUP);
 		bi->memlimit64 = pci_emul_membase64;
 	}