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The flip: PCI enumeration leaves the kernel (M19.3)

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enumeratePci, addBars, pciConfigurationPtr, and the PciHeader struct are
deleted; the kernel seeds only the host bridge, and the ring-3 pci-bus
driver's reports are the sole source of PCI function nodes. The manager
matches PCI drivers from reported identity, deduped by registered device
id so a bus restart never double-spawns.

The flip did its job by exposing a latent SMP race: ring-3
device_register made the broker table concurrent for the first time, and
mmio_map read it lock-free — under load a torn resource length mapped
hpet's window wrong (its user fault) and underflowed r.len-1 into a
kernel integer-overflow panic. Fixed: the broker read in mmio_map (and
claim) runs under the big kernel lock, the arithmetic rejects
zero-length and wrapping windows cleanly, and pci-bus no longer registers
unimplemented size-0 BARs. driver-restart hammered 6x, suite 55/55.
This commit is contained in:
Daniel Samson
2026-07-13 02:54:50 +01:00
parent d26262bf56
commit af2c766f42
7 changed files with 135 additions and 185 deletions
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system/drivers/pci-bus/pci-bus.zig
+4 -1
View File
@@ -180,6 +180,7 @@ fn registerAndReport(bus: u64, dev: u64, function: u64, class_triple: u32) void
configWrite(bus, dev, function, off, original);
const mask = readback & 0xFFFF_FFFC;
const size: u32 = if (mask == 0) 0 else (~mask +% 1) & 0xFFFF;
if (size == 0) continue; // unimplemented BAR — nothing to register
descriptor.resources[slot] = .{ .kind = @intFromEnum(device.ResourceKind.io_port), .start = original & 0xFFFF_FFFC, .len = size };
descriptor.resource_count += 1;
} else if ((original >> 1) & 0x3 == 2) {
@@ -192,15 +193,17 @@ fn registerAndReport(bus: u64, dev: u64, function: u64, class_triple: u32) void
configWrite(bus, dev, function, off + 4, original_high);
const readback = (@as(u64, hi) << 32) | (lo & 0xFFFF_FFF0);
const size: u64 = if (readback == 0) 0 else ~readback +% 1;
i += 1; // consumed the high half regardless
if (size == 0) continue;
descriptor.resources[slot] = .{ .kind = @intFromEnum(device.ResourceKind.memory), .start = (@as(u64, original_high) << 32) | (original & 0xFFFF_FFF0), .len = size };
descriptor.resource_count += 1;
i += 1; // consumed the high half
} else {
configWrite(bus, dev, function, off, 0xFFFF_FFFF);
const readback = configRead(bus, dev, function, off);
configWrite(bus, dev, function, off, original);
const mask = readback & 0xFFFF_FFF0;
const size: u32 = if (mask == 0) 0 else ~mask +% 1;
if (size == 0) continue;
descriptor.resources[slot] = .{ .kind = @intFromEnum(device.ResourceKind.memory), .start = original & 0xFFFF_FFF0, .len = size };
descriptor.resource_count += 1;
}