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ps2: misc controller fixes #1223

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Merged
iximeow merged 2 commits into from
Sep 30, 2026
Merged

ps2: misc controller fixes #1223

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8d9ee79
ps2: controller should survive weird accesses
iximeow Sep 29, 2026
b3d07a4
ps2: controller RAM should be accessible
iximeow Sep 30, 2026
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29 changes: 25 additions & 4 deletions lib/propolis/src/hw/ps2/ctrl.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -291,8 +291,18 @@ const PS2C_CMD_WRITE_AUX_IN: u8 = 0xd4;
const PS2C_CMD_PULSE_START: u8 = 0xf0;
const PS2C_CMD_PULSE_END: u8 = 0xff;

const PS2C_RAM_LEN: usize =
(PS2C_CMD_WRITE_RAM_END - PS2C_CMD_WRITE_RAM_START) as usize;
// PS/2 Controller RAM is modeled as 31 bytes of variable data, with the first
// byte of the controller RAM region (read with command 0x20, written with
// command 0x60) is handled separately through `ctrl_cfg`.
//
// That leaves 31 bytes of controller RAM here.
const PS2C_RAM_LEN: usize = const {
// The command consts above are inclusive of the accessed range, so we must
// add one for the RAM array to span all 31 bytes.
let size = (PS2C_CMD_WRITE_RAM_END - PS2C_CMD_WRITE_RAM_START + 1) as usize;
assert!(size == 31);
size
};

#[derive(Default)]
struct PS2State {
Expand Down Expand Up @@ -399,7 +409,18 @@ impl PS2Ctrl {
}

fn pio_rw(&self, port: u16, rwo: RWOp) {
assert_eq!(rwo.len(), 1);
if rwo.len() != 1 {
// TODO: It would be nice to record an error somewhere.
//
// The guest has operated the PS/2 controller.. poorly. Port
// I/O to the controller's registers should be one byte wide. In
// practice I *think* wider accesses are masked down to the one byte
// that is actually wired up to the port, but behavior in this case
// is not tested. Either way, we haven't (?yet?) seen a PS/2 driver
// that does these kinds of accesses.
return;
}

match port {
ibmpc::PORT_PS2_DATA => match rwo {
RWOp::Read(ro) => ro.write_u8(self.data_read()),
Expand Down Expand Up @@ -434,7 +455,7 @@ impl PS2Ctrl {
state.ctrl_cfg = cfg;
}
PS2C_CMD_WRITE_RAM_START..=PS2C_CMD_WRITE_RAM_END => {
let off = v - PS2C_CMD_WRITE_RAM_START;
let off = prefix - PS2C_CMD_WRITE_RAM_START;
state.ram[off as usize] = v;
}
PS2C_CMD_WRITE_CTLR_OUT => {
Expand Down
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