Cleanly hide DMAR from ACPI so that Linux does not I/O error when ls …

…/sys/firmware/acpi/tables/
lxylxy123456 · Dec 21, 2022 · 93cbd69 · 93cbd69
1 parent 6b2c4d4
commit 93cbd69
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Showing 5 changed files with 55 additions and 4 deletions.
diff --git a/xmhf/src/xmhf-core/include/arch/x86/xmhf-baseplatform-arch-x86.h b/xmhf/src/xmhf-core/include/arch/x86/xmhf-baseplatform-arch-x86.h
@@ -346,6 +346,9 @@ u32 xmhf_baseplatform_arch_flat_readu32(u32 addr);
 //read 64-bits from absolute physical address
 u64 xmhf_baseplatform_arch_flat_readu64(u32 addr);
 
+//write 8-bits to absolute physical address
+void xmhf_baseplatform_arch_flat_writeu8(u32 addr, u8 val);
+
 //write 32-bits to absolute physical address
 void xmhf_baseplatform_arch_flat_writeu32(u32 addr, u32 val);
 

diff --git a/xmhf/src/xmhf-core/include/xmhf-runtime.h b/xmhf/src/xmhf-core/include/xmhf-runtime.h
@@ -88,6 +88,8 @@ extern volatile u32 g_lock_appmain_success_counter __attribute__(( section(".dat
 //exported FUNCTIONS
 //----------------------------------------------------------------------
 
+void vmx_dmar_zap(spa_t dmaraddrphys);
+
 //entry point of EMHF runtime; this is where we get control from the SL
 void xmhf_runtime_entry(void);
 

diff --git a/xmhf/src/xmhf-core/xmhf-runtime/xmhf-baseplatform/arch/x86/bplt-x86-addressing.c b/xmhf/src/xmhf-core/xmhf-runtime/xmhf-baseplatform/arch/x86/bplt-x86-addressing.c
@@ -120,6 +120,20 @@ u64 xmhf_baseplatform_arch_flat_readu64(u32 addr){
 #endif /* !defined(__I386__) && !defined(__AMD64__) */
 }
 
+//write 32-bits to absolute physical address
+void xmhf_baseplatform_arch_flat_writeu8(u32 addr, u8 val) {
+#ifdef __AMD64__
+    *(u8*)(xmhf_baseplatform_arch_flat_pa2va(addr)) = val;
+#elif defined(__I386__)
+    __asm__ __volatile__("movb %%al, %%fs:(%%ebx)\r\n"
+                         :
+                         : "b"(addr), "a"((u32)val)
+                         );
+#else /* !defined(__I386__) && !defined(__AMD64__) */
+    #error "Unsupported Arch"
+#endif /* !defined(__I386__) && !defined(__AMD64__) */
+}
+
 //write 32-bits to absolute physical address
 void xmhf_baseplatform_arch_flat_writeu32(u32 addr, u32 val) {
 #ifdef __AMD64__

diff --git a/xmhf/src/xmhf-core/xmhf-runtime/xmhf-dmaprot/arch/x86/vmx/dmap-vmx-runtime.c b/xmhf/src/xmhf-core/xmhf-runtime/xmhf-dmaprot/arch/x86/vmx/dmap-vmx-runtime.c
@@ -419,7 +419,7 @@ static u32 vmx_eap_initialize(
     // zap VT-d presence in ACPI table...
     // DRHD pages are protected from guest memory access in
     // xmhf_dmaprot_arch_x86_vmx_protect_drhd().
-    xmhf_baseplatform_arch_flat_writeu32(dmaraddrphys, 0UL);
+    vmx_dmar_zap(dmaraddrphys);
 
     // Flush CPU cache
     wbinvd();

diff --git a/xmhf/src/xmhf-core/xmhf-runtime/xmhf-startup/runtime.c b/xmhf/src/xmhf-core/xmhf-runtime/xmhf-startup/runtime.c
@@ -50,6 +50,40 @@
 //---includes-------------------------------------------------------------------
 #include <xmhf.h>
 
+#if defined(__DRT__) || defined(__DMAP__)
+
+/* Size of ACPI DESCRIPTION_HEADER Fields */
+#define ACPI_DESC_HEADER_SIZE 36
+
+/* Offset of interesting DESCRIPTION_HEADER fields */
+#define ACPI_DESC_SIGNATURE_OFF 0
+#define ACPI_DESC_LENGTH_OFF 4
+#define ACPI_DESC_CHECKSUM_OFF 9
+
+/*
+ * Given the address of ACPI DMAR table, change it to something else so that
+ * the red OS thinks there is no DMAR table present. Currently changing to a
+ * table with signature "XMHF".
+ */
+void vmx_dmar_zap(spa_t dmaraddrphys)
+{
+	u8 buffer[ACPI_DESC_HEADER_SIZE];
+	u8 checksum = 0;
+	/* Signature: "XMHF" */
+	xmhf_baseplatform_arch_flat_writeu32(dmaraddrphys + ACPI_DESC_SIGNATURE_OFF, 0x46484d58UL);
+	/* Length: 36 */
+	xmhf_baseplatform_arch_flat_writeu32(dmaraddrphys + ACPI_DESC_LENGTH_OFF, 36UL);
+	/* Compute checksum */
+	xmhf_baseplatform_arch_flat_copy(buffer, (u8 *)dmaraddrphys, ACPI_DESC_HEADER_SIZE);
+	buffer[ACPI_DESC_CHECKSUM_OFF] = 0;
+	for (size_t i = 0; i < ACPI_DESC_HEADER_SIZE; i++) {
+		checksum -= buffer[i];
+	}
+	xmhf_baseplatform_arch_flat_writeu8(dmaraddrphys + ACPI_DESC_CHECKSUM_OFF, checksum);
+}
+
+#endif /* defined(__DRT__) || defined(__DMAP__) */
+
 #if defined(__DRT__) && !defined(__DMAP__)
 
 // This macro is defined in xmhf-dmaprot.h. However when !__DMAP__ this header
@@ -74,7 +108,6 @@ static void vmx_eap_zap(void)
     memset(&rsdt, 0, sizeof(ACPI_RSDT));
 
     // get ACPI RSDP
-    // [TODO] Unify the name of <xmhf_baseplatform_arch_x86_acpi_getRSDP> and <xmhf_baseplatform_arch_x86_acpi_getRSDP>, and then remove the following #ifdef
     status = xmhf_baseplatform_arch_x86_acpi_getRSDP(&rsdp);
     HALT_ON_ERRORCOND(status != 0); // we need a valid RSDP to proceed
     printf("%s: RSDP at %08x\n", __FUNCTION__, status);
@@ -137,7 +170,7 @@ static void vmx_eap_zap(void)
     // zap VT-d presence in ACPI table...
     // TODO: we need to be a little elegant here. eventually need to setup
     // EPT/NPTs such that the DMAR pages are unmapped for the guest
-    xmhf_baseplatform_arch_flat_writeu32(dmaraddrphys, 0UL);
+    vmx_dmar_zap(dmaraddrphys);
 
     // success
     printf("%s: success, leaving...\n", __FUNCTION__);
@@ -193,7 +226,6 @@ void xmhf_runtime_entry(void){
 	#endif
 
 #if defined (__DMAP__)
-		// TODO: DMAP code not ported to amd64 yet
 		{
 			#define ADDR_512GB  (PAGE_SIZE_512G)
 				u64 protectedbuffer_paddr;