hv: pSRAM: temporarily remove NX bit of PTCM binary

Temporarily remove NX bit of PTCM binary in pagetable during pSRAM
initialization:
1.added a function ppt_set_nx_bit to temporarily remove/restore the NX bit of
a given area in pagetable.
2.Temporarily remove NX bit of PTCM binary during pSRAM initialization to make
PTCM codes executable.
3. TODO: We may use SMP call to flush TLB and do pSRAM initilization on APs.

Tracked-On: #5330
Signed-off-by: Qian Wang <qian1.wang@intel.com>
Acked-by: Eddie Dong <eddie.dong@intel.com>

hypervisor/arch/x86/mmu.c

@@ -210,6 +210,21 @@ void hv_access_memory_region_update(uint64_t base, uint64_t size)
 		round_pde_up(size_aligned), 0UL, PAGE_USER, &ppt_mem_ops, MR_MODIFY);
 }
 
+void ppt_set_nx_bit(uint64_t base, uint64_t size, bool add)
+{
+	uint64_t region_end = base + size;
+	uint64_t base_aligned = round_pde_down(base);
+	uint64_t size_aligned = round_pde_up(region_end - base_aligned);
+
+	if (add) {
+		mmu_modify_or_del((uint64_t *)ppt_mmu_pml4_addr,
+			base_aligned, size_aligned, PAGE_NX, 0UL, &ppt_mem_ops, MR_MODIFY);
+	} else {
+		mmu_modify_or_del((uint64_t *)ppt_mmu_pml4_addr,
+			base_aligned, size_aligned, 0UL, PAGE_NX, &ppt_mem_ops, MR_MODIFY);
+	}
+}
+
 void init_paging(void)
 {
 	uint64_t hv_hva;

hypervisor/arch/x86/ptcm.c

@@ -23,6 +23,23 @@ static struct ptct_entry_data_ptcm_binary *ptcm_binary = NULL;
 
 static struct acpi_table_header *acpi_ptct_tbl = NULL;
 
+static inline void ptcm_set_nx(bool add)
+{
+	ppt_set_nx_bit((uint64_t)hpa2hva(ptcm_binary->address), ptcm_binary->size, add);
+}
+
+static inline void ptcm_flush_binary_tlb(void)
+{
+	uint64_t linear_addr, start_addr = (uint64_t)hpa2hva(ptcm_binary->address);
+	uint64_t end_addr = start_addr + ptcm_binary->size;
+
+	for (linear_addr = start_addr; linear_addr < end_addr; linear_addr += PAGE_SIZE) {
+		invlpg(linear_addr);
+	}
+
+}
+
+
 static inline void *get_ptct_address()
 {
 	return (void *)acpi_ptct_tbl + sizeof(*acpi_ptct_tbl);
@@ -99,8 +116,11 @@ void init_psram(bool is_bsp)
 	 * That's why we add "!is_psram_initialized" as an condition.
 	 */
 	if (!is_psram_initialized && (acpi_ptct_tbl != NULL)) {
+		/* TODO: We may use SMP call to flush TLB and do pSRAM initilization on APs */
 		if (is_bsp) {
 			parse_ptct();
+			/* Clear the NX bit of PTCM area */
+			ptcm_set_nx(false);
 			bitmap_clear_lock(get_pcpu_id(), &init_psram_cpus_mask);
 		}
 
@@ -111,6 +131,8 @@ void init_psram(bool is_bsp)
 			ptcm_binary->address, header->magic, header->version);
 		ASSERT(header->magic == PTCM_MAGIC, "Incorrect PTCM magic!");
 
+		/* Flush the TLB, so that BSP/AP can execute the PTCM ABI */
+		ptcm_flush_binary_tlb();
 		ptcm_command_func = (ptcm_abi_func)(hpa2hva(ptcm_binary->address) + header->command_offset);
 		pr_info("ptcm command function is found at %llx",ptcm_command_func);
 		ptcm_ret_code = ptcm_command_func(PTCM_CMD_INIT_PSRAM, get_ptct_address());
@@ -118,8 +140,15 @@ void init_psram(bool is_bsp)
 		/* return 0 for success, -1 for failure */
 		ASSERT(ptcm_ret_code == 0);
 
+		if (is_bsp) {
+			/* Restore the NX bit of PTCM area in page table */
+			ptcm_set_nx(true);
+		}
+
 		bitmap_set_lock(get_pcpu_id(), &init_psram_cpus_mask);
 		wait_sync_change(&init_psram_cpus_mask, ALL_CPUS_MASK);
+		/* Flush the TLB on BSP and all APs to restore the NX for pSRAM area */
+		ptcm_flush_binary_tlb();
 
 		if (is_bsp) {
 			is_psram_initialized = true;

hypervisor/include/arch/x86/mmu.h

@@ -114,6 +114,7 @@ void mmu_add(uint64_t *pml4_page, uint64_t paddr_base, uint64_t vaddr_base,
 void mmu_modify_or_del(uint64_t *pml4_page, uint64_t vaddr_base, uint64_t size,
 		uint64_t prot_set, uint64_t prot_clr, const struct memory_ops *mem_ops, uint32_t type);
 void hv_access_memory_region_update(uint64_t base, uint64_t size);
+void ppt_set_nx_bit(uint64_t base, uint64_t size, bool add);
 
 /**
  * @brief Specified signle VPID flush
@@ -150,6 +151,11 @@ void flush_address_space(void *addr, uint64_t size);
  */
 void invept(const void *eptp);
 
+static inline void invlpg(unsigned long addr)
+{
+	asm volatile("invlpg (%0)" ::"r" (addr) : "memory");
+}
+
 static inline void cache_flush_invalidate_all(void)
 {
 	asm volatile ("   wbinvd\n" : : : "memory");