feat: SMP stage 1 (4 harts, per-hart guarded stacks, home-core affinity, IPIs, TLB shootdown, one temporary kernel lock), 4-core storm

crates/adapter-riscv/src/platform.rs

@@ -10,6 +10,7 @@ use types::{
 use crate::board;
 use crate::hw::{plic::Plic, timer};
 use crate::mmu;
+use crate::smp;
 use crate::trap;
 
 pub struct RiscVPlatform {
@@ -20,9 +21,9 @@ pub struct RiscVPlatform {
 }
 
 impl RiscVPlatform {
-    pub fn new(kernel_pt_addr: usize) -> Self {
+    pub fn new(kernel_pt_addr: usize, num_cores: u8) -> Self {
         Self {
-            num_cores: 1,
+            num_cores,
             kernel_pt: kernel_pt_addr,
             page_tables: [0usize; MAX_PROCESSES],
         }
@@ -63,8 +64,10 @@ impl Platform for RiscVPlatform {
         let Some(root) = self.root(process) else {
             return;
         };
-        // The caller may be tearing down the space we are running on; get
-        // off it before the kernel frees its frames.
+        // No hart may still translate through it once the kernel frees its
+        // frames: other harts leave it (and wait for nothing but that), and
+        // the caller may be tearing down the space we are running on.
+        smp::shoot_down(root);
         if mmu::active_root() == root {
             // SAFETY: the kernel page table lives in the boot heap forever.
             mmu::activate(unsafe { &*(self.kernel_pt as *const mmu::PageTable) });
@@ -95,6 +98,8 @@ impl Platform for RiscVPlatform {
     fn unmap_page(&mut self, process: ProcessId, va: VirtualAddress) {
         if let Some(root) = self.root(process) {
             mmu::unmap_user_page(root, va.raw());
+            // Other harts running this process may still cache it.
+            smp::shoot_down(root);
         }
     }
 
@@ -144,10 +149,12 @@ impl Platform for RiscVPlatform {
         Plic::enable(irq.raw() as u32);
     }
 
-    fn send_ipi(&mut self, _target: CoreId) {}
+    fn send_ipi(&mut self, target: CoreId) {
+        smp::kick(target.raw() as usize);
+    }
 
     fn core_id(&self) -> CoreId {
-        CoreId::from_raw(0)
+        CoreId::from_raw(smp::hart_id() as u8)
     }
 
     fn num_cores(&self) -> u8 {