[kvm-unit-tests v3 3/4] x86: Add test cases for LAM_{U48,U57}

[Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>]

This unit test covers:
1. CR3 LAM bits toggles.
2. Memory/MMIO access with user mode address containing LAM metadata.

Signed-off-by: Binbin Wu <binbin.wu@xxxxxxxxxxxxxxx>
---
 lib/x86/processor.h |  2 ++
 x86/lam.c           | 71 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 73 insertions(+)

diff --git a/lib/x86/processor.h b/lib/x86/processor.h
index 4bb8cd7..a181e0b 100644
--- a/lib/x86/processor.h
+++ b/lib/x86/processor.h
@@ -56,7 +56,9 @@
 
 #define X86_CR3_PCID_MASK	GENMASK(11, 0)
 #define X86_CR3_LAM_U57_BIT	(61)
+#define X86_CR3_LAM_U57		BIT_ULL(X86_CR3_LAM_U57_BIT)
 #define X86_CR3_LAM_U48_BIT	(62)
+#define X86_CR3_LAM_U48		BIT_ULL(X86_CR3_LAM_U48_BIT)
 
 #define X86_CR4_VME_BIT		(0)
 #define X86_CR4_VME		BIT(X86_CR4_VME_BIT)
diff --git a/x86/lam.c b/x86/lam.c
index 63c3fde..50bcdf5 100644
--- a/x86/lam.c
+++ b/x86/lam.c
@@ -18,9 +18,11 @@
 #include "vm.h"
 #include "asm/io.h"
 #include "ioram.h"
+#include "usermode.h"
 
 #define LAM57_MASK	GENMASK_ULL(62, 57)
 #define LAM48_MASK	GENMASK_ULL(62, 48)
+#define CR3_LAM_BITS_MASK (X86_CR3_LAM_U48 | X86_CR3_LAM_U57)
 
 #define FLAGS_LAM_ACTIVE	BIT_ULL(0)
 #define FLAGS_LA57		BIT_ULL(1)
@@ -41,6 +43,16 @@ static inline bool lam_sup_active(void)
 	return !!(read_cr4() & X86_CR4_LAM_SUP);
 }
 
+static inline bool lam_u48_active(void)
+{
+	return (read_cr3() & CR3_LAM_BITS_MASK) == X86_CR3_LAM_U48;
+}
+
+static inline bool lam_u57_active(void)
+{
+	return !!(read_cr3() & X86_CR3_LAM_U57);
+}
+
 /* According to LAM mode, set metadata in high bits */
 static inline u64 set_metadata(u64 src, u64 metadata_mask)
 {
@@ -92,6 +104,7 @@ static void do_mov(void *mem)
 static u64 test_ptr(u64 arg1, u64 arg2, u64 arg3, u64 arg4)
 {
 	bool lam_active = !!(arg1 & FLAGS_LAM_ACTIVE);
+	bool la_57 = !!(arg1 & FLAGS_LA57);
 	u64 lam_mask = arg2;
 	u64 *ptr = (u64 *)arg3;
 	bool is_mmio = !!arg4;
@@ -105,6 +118,17 @@ static u64 test_ptr(u64 arg1, u64 arg2, u64 arg3, u64 arg4)
 	report(fault != lam_active,"Test tagged addr (%s)",
 	       is_mmio ? "MMIO" : "Memory");
 
+	/*
+	 * This test case is only triggered when LAM_U57 is active and 4-level
+	 * paging is used. For the case, bit[56:47] aren't all 0 triggers #GP.
+	 */
+	if (lam_active && (lam_mask == LAM57_MASK) && !la_57) {
+		ptr = (u64 *)set_metadata((u64)ptr, LAM48_MASK);
+		fault = test_for_exception(GP_VECTOR, do_mov, ptr);
+		report(fault,  "Test non-LAM-canonical addr (%s)",
+		       is_mmio ? "MMIO" : "Memory");
+	}
+
 	return 0;
 }
 
@@ -221,6 +245,52 @@ static void test_lam_sup(bool has_lam, bool fep_available)
 		test_invlpg(lam_mask, vaddr, true);
 }
 
+static void test_lam_user_mode(bool has_lam, u64 lam_mask, u64 mem, u64 mmio)
+{
+	unsigned r;
+	bool raised_vector;
+	unsigned long cr3 = read_cr3() & ~CR3_LAM_BITS_MASK;
+	u64 flags = 0;
+
+	if (is_la57())
+		flags |= FLAGS_LA57;
+
+	if (has_lam) {
+		if (lam_mask == LAM48_MASK) {
+			r = write_cr3_safe(cr3 | X86_CR3_LAM_U48);
+			report((r == 0) && lam_u48_active(), "Set LAM_U48");
+		} else {
+			r = write_cr3_safe(cr3 | X86_CR3_LAM_U57);
+			report((r == 0) && lam_u57_active(), "Set LAM_U57");
+		}
+	}
+	if (lam_u48_active() || lam_u57_active())
+		flags |= FLAGS_LAM_ACTIVE;
+
+	run_in_user((usermode_func)test_ptr, GP_VECTOR, flags, lam_mask, mem,
+		    false, &raised_vector);
+	run_in_user((usermode_func)test_ptr, GP_VECTOR, flags, lam_mask, mmio,
+		    true, &raised_vector);
+}
+
+static void test_lam_user(bool has_lam)
+{
+	phys_addr_t paddr;
+	unsigned long cr3 = read_cr3();
+
+	/*
+	 * The physical address width is within 36 bits, so that using identical
+	 * mapping, the linear address will be considered as user mode address
+	 * from the view of LAM.
+	 */
+	paddr = virt_to_phys(alloc_page());
+	install_page((void *)cr3, paddr, (void *)paddr);
+	install_page((void *)cr3, IORAM_BASE_PHYS, (void *)IORAM_BASE_PHYS);
+
+	test_lam_user_mode(has_lam, LAM48_MASK, paddr, IORAM_BASE_PHYS);
+	test_lam_user_mode(has_lam, LAM57_MASK, paddr, IORAM_BASE_PHYS);
+}
+
 int main(int ac, char **av)
 {
 	bool has_lam;
@@ -239,6 +309,7 @@ int main(int ac, char **av)
 			    "use kvm.force_emulation_prefix=1 to enable\n");
 
 	test_lam_sup(has_lam, fep_available);
+	test_lam_user(has_lam);
 
 	return report_summary();
 }
-- 
2.25.1