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feat(amd64): add a bunch of stuff

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Loïc Grégoire
2026-04-15 19:37:24 -04:00
parent 986fe82383
commit a7cdfeb57a
4 changed files with 322 additions and 130 deletions
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src/platform/pc/pvclock.zig
+4 -38
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@@ -1,22 +1,11 @@
const amd64 = @import("arch");
const kvm = amd64.hypervisor.kvm;
const b = @import("base");
const std = @import("std");
const mm = b.mm;
const ke = b.ke;
const PVClock = extern struct {
version: u32,
pad0: u32,
tsc_timestamp: u64,
system_time: u64,
tsc_to_system_mul: u32,
tsc_shift: i8,
flags: u8,
pad1: [2]u8,
};
var pvclock: *PVClock = undefined;
var pvclock_src: kvm.PVClockSource = undefined;
var pvclock_tc: ke.TimeCounter = .{
.name = "pvclock",
.quality = 75,
@@ -27,35 +16,12 @@ var pvclock_tc: ke.TimeCounter = .{
.n = 0,
};
var time_at_boot: u64 = 0;
pub fn init() linksection(b.init) void {
const page = mm.phys.alloc();
pvclock = @ptrFromInt(mm.p2v(page));
amd64.write_msr(.KvmSystemTimeNew, page | 1);
time_at_boot = read_pvclock();
pvclock_src = kvm.PVClockSource.init(page, mm.p2v(page));
ke.time.register_source(&pvclock_tc);
}
fn read_pvclock() u64 {
while (true) {
const ver = b.mmio_read(u32, @intFromPtr(&pvclock.version));
if (ver & 1 != 0) continue; // Update in progress.
const tsc_shift = b.mmio_read(i8, @intFromPtr(&pvclock.tsc_shift));
const tsc_delta = amd64.rdtsc() - b.mmio_read(u64, @intFromPtr(&pvclock.tsc_timestamp));
const shifted = if (tsc_shift >= 0)
tsc_delta << @intCast(tsc_shift)
else
tsc_delta >> @intCast(-tsc_shift);
const ns = b.mmio_read(u64, @intFromPtr(&pvclock.system_time)) +
(shifted * @as(u128, b.mmio_read(u32, @intFromPtr(&pvclock.tsc_to_system_mul))) >> 32);
if (b.mmio_read(u32, @intFromPtr(&pvclock.version)) == ver) return @as(u64, @truncate(ns)) - time_at_boot;
}
return pvclock_src.read();
}