From a4223742a63da5274b8cb2d5210df0215e2a0b57 Mon Sep 17 00:00:00 2001
From: Peter Fang <peter.fang@intel.com>
Date: Fri, 18 Oct 2024 00:24:47 -0700
Subject: [PATCH] platform: tdp: Implement page validation interfaces

On TDP platforms, page validation means page acceptance. Implement
validate_{physical, virtual}_page_range() using the tdx-tdcall crate for
this TDCALL operation. Page invalidation simply means zeroing out the
page on TDP platforms.

Signed-off-by: Peter Fang <peter.fang@intel.com>
---
 kernel/src/platform/mod.rs |  2 +-
 kernel/src/platform/tdp.rs | 43 ++++++++++++++++++++++++++++++--------
 2 files changed, 35 insertions(+), 10 deletions(-)

diff --git a/kernel/src/platform/mod.rs b/kernel/src/platform/mod.rs
index e9171d451..1a6cd68c4 100644
--- a/kernel/src/platform/mod.rs
+++ b/kernel/src/platform/mod.rs
@@ -98,7 +98,7 @@ pub trait SvsmPlatform {
 
     /// Marks a virtual range of pages as valid or invalid for use as private
     /// pages.  Provided primarily for use in stage2 where validation by
-    /// physical address cannot e supported.
+    /// physical address cannot be supported.
     fn validate_virtual_page_range(
         &self,
         region: MemoryRegion<VirtAddr>,
diff --git a/kernel/src/platform/tdp.rs b/kernel/src/platform/tdp.rs
index 2bfb1eca4..bb210c14b 100644
--- a/kernel/src/platform/tdp.rs
+++ b/kernel/src/platform/tdp.rs
@@ -10,13 +10,14 @@ use crate::cpu::cpuid::CpuidResult;
 use crate::cpu::percpu::PerCpu;
 use crate::error::SvsmError;
 use crate::io::IOPort;
+use crate::mm::{virt_to_frame, PerCPUPageMappingGuard};
 use crate::platform::{PageEncryptionMasks, PageStateChangeOp, PageValidateOp, SvsmPlatform};
 use crate::types::PageSize;
 use crate::utils::immut_after_init::ImmutAfterInitCell;
-use crate::utils::MemoryRegion;
+use crate::utils::{zero_mem_region, MemoryRegion};
 use tdx_tdcall::tdx::{
-    tdvmcall_io_read_16, tdvmcall_io_read_32, tdvmcall_io_read_8, tdvmcall_io_write_16,
-    tdvmcall_io_write_32, tdvmcall_io_write_8,
+    td_accept_memory, tdvmcall_io_read_16, tdvmcall_io_read_32, tdvmcall_io_read_8,
+    tdvmcall_io_write_16, tdvmcall_io_write_32, tdvmcall_io_write_8,
 };
 
 static GHCI_IO_DRIVER: GHCIIOPort = GHCIIOPort::new();
@@ -93,18 +94,42 @@ impl SvsmPlatform for TdpPlatform {
 
     fn validate_physical_page_range(
         &self,
-        _region: MemoryRegion<PhysAddr>,
-        _op: PageValidateOp,
+        region: MemoryRegion<PhysAddr>,
+        op: PageValidateOp,
     ) -> Result<(), SvsmError> {
-        Err(SvsmError::Tdx)
+        match op {
+            PageValidateOp::Validate => {
+                td_accept_memory(region.start().into(), region.len().try_into().unwrap());
+            }
+            PageValidateOp::Invalidate => {
+                let mapping = PerCPUPageMappingGuard::create(region.start(), region.end(), 0)?;
+                zero_mem_region(mapping.virt_addr(), mapping.virt_addr() + region.len());
+            }
+        }
+        Ok(())
     }
 
     fn validate_virtual_page_range(
         &self,
-        _region: MemoryRegion<VirtAddr>,
-        _op: PageValidateOp,
+        region: MemoryRegion<VirtAddr>,
+        op: PageValidateOp,
     ) -> Result<(), SvsmError> {
-        Err(SvsmError::Tdx)
+        match op {
+            PageValidateOp::Validate => {
+                let mut va = region.start();
+                while va < region.end() {
+                    let pa = virt_to_frame(va);
+                    let sz = pa.end() - pa.address();
+                    // td_accept_memory() will take care of alignment
+                    td_accept_memory(pa.address().into(), sz.try_into().unwrap());
+                    va = va + sz;
+                }
+            }
+            PageValidateOp::Invalidate => {
+                zero_mem_region(region.start(), region.end());
+            }
+        }
+        Ok(())
     }
 
     fn configure_alternate_injection(&mut self, _alt_inj_requested: bool) -> Result<(), SvsmError> {