panic: size 22400, No vmcore

KDB: debugger backends: ddb
KDB: current backend: ddb
---<<BOOT>>---
Copyright (c) 1992-2022 The FreeBSD Project.
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	The Regents of the University of California. All rights reserved.
FreeBSD is a registered trademark of The FreeBSD Foundation.
FreeBSD 14.0-CURRENT #4 main-n255677-71fe907dfb03c-dirty: Wed May 18 12:07:30 CEST 2022
    pho@mercat1.netperf.freebsd.org:/usr/src/sys/amd64/compile/PHO amd64
FreeBSD clang version 13.0.0 (git@github.com:llvm/llvm-project.git llvmorg-13.0.0-0-gd7b669b3a303)
WARNING: WITNESS option enabled, expect reduced performance.
WARNING: DIAGNOSTIC option enabled, expect reduced performance.
VT(vga): resolution 640x480
CPU: Intel(R) Xeon(R) CPU E5-1650 v3 @ 3.50GHz (3500.17-MHz K8-class CPU)
  Origin="GenuineIntel"  Id=0x306f2  Family=0x6  Model=0x3f  Stepping=2
  Features=0xbfebfbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,CLFLUSH,DTS,ACPI,MMX,FXSR,SSE,SSE2,SS,HTT,TM,PBE>
  Features2=0x7ffefbff<SSE3,PCLMULQDQ,DTES64,MON,DS_CPL,VMX,SMX,EST,TM2,SSSE3,SDBG,FMA,CX16,xTPR,PDCM,PCID,DCA,SSE4.1,SSE4.2,x2APIC,MOVBE,POPCNT,TSCDLT,AESNI,XSAVE,OSXSAVE,AVX,F16C,RDRAND>
  AMD Features=0x2c100800<SYSCALL,NX,Page1GB,RDTSCP,LM>
  AMD Features2=0x21<LAHF,ABM>
  Structured Extended Features=0x37ab<FSGSBASE,TSCADJ,BMI1,AVX2,SMEP,BMI2,ERMS,INVPCID,PQM,NFPUSG>
  XSAVE Features=0x1<XSAVEOPT>
  VT-x: PAT,HLT,MTF,PAUSE,EPT,UG,VPID,VID,PostIntr
  TSC: P-state invariant, performance statistics
real memory  = 34359738368 (32768 MB)
avail memory = 33176645632 (31639 MB)
Event timer "LAPIC" quality 600
ACPI APIC Table: <SUPERM SMCI--MB>
FreeBSD/SMP: Multiprocessor System Detected: 12 CPUs
FreeBSD/SMP: 1 package(s) x 6 core(s) x 2 hardware threads
random: registering fast source Intel Secure Key RNG
random: fast provider: "Intel Secure Key RNG"
random: unblocking device.
ioapic0 <Version 2.0> irqs 0-23
ioapic1 <Version 2.0> irqs 24-47
Launching APs: 1 5 10 11 2 6 3 7 4 8 9
random: entropy device external interface
kbd1 at kbdmux0
vtvga0: <VT VGA driver>
smbios0: <System Management BIOS> at iomem 0xf0560-0xf057e
smbios0: Version: 2.8, BCD Revision: 2.7
aesni0: <AES-CBC,AES-CCM,AES-GCM,AES-ICM,AES-XTS>
acpi0: <SUPERM SMCI--MB>
acpi0: Power Button (fixed)
cpu0: <ACPI CPU> on acpi0
dmar0: <DMA remap> iomem 0xfbffc000-0xfbffcfff on acpi0
atrtc0: <AT realtime clock> port 0x70-0x71,0x74-0x77 irq 8 on acpi0
atrtc0: registered as a time-of-day clock, resolution 1.000000s
Event timer "RTC" frequency 32768 Hz quality 0
attimer0: <AT timer> port 0x40-0x43,0x50-0x53 irq 0 on acpi0
Timecounter "i8254" frequency 1193182 Hz quality 0
Event timer "i8254" frequency 1193182 Hz quality 100
hpet0: <High Precision Event Timer> iomem 0xfed00000-0xfed003ff on acpi0
Timecounter "HPET" frequency 14318180 Hz quality 950
Event timer "HPET" frequency 14318180 Hz quality 350
Event timer "HPET1" frequency 14318180 Hz quality 340
Event timer "HPET2" frequency 14318180 Hz quality 340
Event timer "HPET3" frequency 14318180 Hz quality 340
Event timer "HPET4" frequency 14318180 Hz quality 340
Event timer "HPET5" frequency 14318180 Hz quality 340
Event timer "HPET6" frequency 14318180 Hz quality 340
Event timer "HPET7" frequency 14318180 Hz quality 340
Timecounter "ACPI-fast" frequency 3579545 Hz quality 900
acpi_timer0: <24-bit timer at 3.579545MHz> port 0x408-0x40b on acpi0
pcib0: <ACPI Host-PCI bridge> on acpi0
pci0: <ACPI PCI bus> on pcib0
pci0: <dasp, performance counters> at device 11.1 (no driver attached)
pci0: <dasp, performance counters> at device 11.2 (no driver attached)
pci0: <dasp, performance counters> at device 16.1 (no driver attached)
pci0: <dasp, performance counters> at device 16.6 (no driver attached)
pci0: <dasp, performance counters> at device 18.1 (no driver attached)
acpi_syscontainer0: <System Container> on acpi0
acpi_syscontainer1: <System Container> on acpi0
acpi_syscontainer2: <System Container> on acpi0
acpi_syscontainer3: <System Container> on acpi0
apei0: <ACPI Platform Error Interface> on acpi0
pcib1: <ACPI Host-PCI bridge> port 0xcf8-0xcff on acpi0
pci1: <ACPI PCI bus> on pcib1
pcib2: <ACPI PCI-PCI bridge> irq 26 at device 1.0 on pci1
pci2: <ACPI PCI bus> on pcib2
pcib3: <ACPI PCI-PCI bridge> irq 32 at device 2.0 on pci1
pci3: <ACPI PCI bus> on pcib3
pci3: <network, ethernet> at device 0.0 (no driver attached)
pci3: <network, ethernet> at device 0.1 (no driver attached)
pcib4: <ACPI PCI-PCI bridge> irq 40 at device 3.0 on pci1
pci4: <ACPI PCI bus> on pcib4
pci1: <unknown> at device 17.0 (no driver attached)
ahci0: <Intel Wellsburg AHCI SATA controller> port 0xf110-0xf117,0xf100-0xf103,0xf0f0-0xf0f7,0xf0e0-0xf0e3,0xf020-0xf03f mem 0xfb438000-0xfb4387ff irq 16 at device 17.4 on pci1
unknown: dmar0 pci0:0:20:0 rid a0 domain 0 mgaw 48 agaw 48 re-mapped
unknown: dmar0 pci0:0:26:0 rid d0 domain 1 mgaw 48 agaw 48 re-mapped
unknown: dmar0 pci0:0:29:0 rid e8 domain 2 mgaw 48 agaw 48 re-mapped
ahci0: dmar0 pci0:0:17:4 rid 8c domain 3 mgaw 48 agaw 48 re-mapped
ahci0: AHCI v1.30 with 4 6Gbps ports, Port Multiplier not supported
ahcich0: <AHCI channel> at channel 0 on ahci0
panic: size 22400
cpuid = 10
time = 1
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xffffffff82364590
vpanic() at vpanic+0x17f/frame 0xffffffff823645e0
panic() at panic+0x43/frame 0xffffffff82364640
iommu_gas_map() at iommu_gas_map+0x230/frame 0xffffffff823646d0
iommu_bus_dmamap_load_something() at iommu_bus_dmamap_load_something+0x10f/frame 0xffffffff82364780
iommu_bus_dmamap_load_buffer() at iommu_bus_dmamap_load_buffer+0x1c5/frame 0xffffffff82364820
bus_dmamap_load() at bus_dmamap_load+0x86/frame 0xffffffff823648a0
ahci_ch_attach() at ahci_ch_attach+0x4ec/frame 0xffffffff82364950
device_attach() at device_attach+0x3c1/frame 0xffffffff82364990
device_probe_and_attach() at device_probe_and_attach+0x70/frame 0xffffffff823649c0
bus_generic_attach() at bus_generic_attach+0x18/frame 0xffffffff823649e0
ahci_attach() at ahci_attach+0x8d7/frame 0xffffffff82364a30
ahci_pci_attach() at ahci_pci_attach+0xa3b/frame 0xffffffff82364aa0
device_attach() at device_attach+0x3c1/frame 0xffffffff82364ae0
device_probe_and_attach() at device_probe_and_attach+0x70/frame 0xffffffff82364b10
bus_generic_attach() at bus_generic_attach+0x18/frame 0xffffffff82364b30
pci_attach() at pci_attach+0xe0/frame 0xffffffff82364b70
acpi_pci_attach() at acpi_pci_attach+0x19/frame 0xffffffff82364bc0
device_attach() at device_attach+0x3c1/frame 0xffffffff82364c00
device_probe_and_attach() at device_probe_and_attach+0x70/frame 0xffffffff82364c30
bus_generic_attach() at bus_generic_attach+0x18/frame 0xffffffff82364c50
acpi_pcib_acpi_attach() at acpi_pcib_acpi_attach+0x42d/frame 0xffffffff82364cb0
device_attach() at device_attach+0x3c1/frame 0xffffffff82364cf0
device_probe_and_attach() at device_probe_and_attach+0x70/frame 0xffffffff82364d20
bus_generic_attach() at bus_generic_attach+0x18/frame 0xffffffff82364d40
acpi_probe_children() at acpi_probe_children+0x207/frame 0xffffffff82364da0
acpi_attach() at acpi_attach+0x9a6/frame 0xffffffff82364e30
device_attach() at device_attach+0x3c1/frame 0xffffffff82364e70
device_probe_and_attach() at device_probe_and_attach+0x70/frame 0xffffffff82364ea0
bus_generic_attach() at bus_generic_attach+0x18/frame 0xffffffff82364ec0
device_attach() at device_attach+0x3c1/frame 0xffffffff82364f00
device_probe_and_attach() at device_probe_and_attach+0x70/frame 0xffffffff82364f30
bus_generic_new_pass() at bus_generic_new_pass+0xed/frame 0xffffffff82364f60
bus_set_pass() at bus_set_pass+0x46/frame 0xffffffff82364f90
configure() at configure+0x9/frame 0xffffffff82364fa0
mi_startup() at mi_startup+0x20f/frame 0xffffffff82364ff0
btext() at btext+0x22
KDB: enter: panic
[ thread pid 0 tid 100000 ]
Stopped at      kdb_enter+0x32: movq    $0,0x12793c3(%rip)
db> x/s version
version:        FreeBSD 14.0-CURRENT #4 main-n255677-71fe907dfb03c-dirty: Wed May 18 12:07:30 CEST 2022\012    pho@mercat1.netperf.freebsd.org:/usr/src/sys/amd64/compile/PHO\012
db> 

diff --git a/sys/dev/iommu/busdma_iommu.c b/sys/dev/iommu/busdma_iommu.c
index 99d47f0b6ede8..70d903b70818b 100644
--- a/sys/dev/iommu/busdma_iommu.c
+++ b/sys/dev/iommu/busdma_iommu.c
@@ -584,7 +584,7 @@ iommu_bus_dmamap_load_something1(struct bus_dma_tag_iommu *tag,
 		}
 		buflen1 = buflen > tag->common.maxsegsz ?
 		    tag->common.maxsegsz : buflen;
-		size = round_page(offset + buflen1);
+		size = buflen1;
 
 		/*
 		 * (Too) optimistically allow split if there are more
@@ -600,24 +600,7 @@ iommu_bus_dmamap_load_something1(struct bus_dma_tag_iommu *tag,
 		    gas_flags, ma + idx, &entry);
 		if (error != 0)
 			break;
-		if ((gas_flags & IOMMU_MF_CANSPLIT) != 0) {
-			KASSERT(size >= entry->end - entry->start,
-			    ("split increased entry size %jx %jx %jx",
-			    (uintmax_t)size, (uintmax_t)entry->start,
-			    (uintmax_t)entry->end));
-			size = entry->end - entry->start;
-			if (buflen1 > size)
-				buflen1 = size;
-		} else {
-			KASSERT(entry->end - entry->start == size,
-			    ("no split allowed %jx %jx %jx",
-			    (uintmax_t)size, (uintmax_t)entry->start,
-			    (uintmax_t)entry->end));
-		}
-		if (offset + buflen1 > size)
-			buflen1 = size - offset;
-		if (buflen1 > tag->common.maxsegsz)
-			buflen1 = tag->common.maxsegsz;
+		buflen1 = entry->end - entry->start;
 
 		KASSERT(vm_addr_align_ok(entry->start + offset,
 		    tag->common.alignment),

Test scenario: boot w/ hw.dmar.enable=1