Add a simple test that runs a 32-bit code segment with two-level page tables.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 x86/svm_tests.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)

diff --git a/x86/svm_tests.c b/x86/svm_tests.c
index 95d18359..3ba3b09c 100644
--- a/x86/svm_tests.c
+++ b/x86/svm_tests.c
@@ -769,6 +769,117 @@ static bool check_mode_switch(struct svm_test *test)
 	return test->scratch == 2;
 }
 
+/*
+ * 32-bit guest tests.  These tests run a tiny guest in legacy 32-bit
+ * protected mode, with either 2-level (non-PAE) or 3-level (PAE) paging.
+ * The guest code is in the low 4 GB and is identity-mapped using large
+ * pages.  The guest issues a few VMMCALLs and then spins; since no
+ * interrupts are taken, the rest of the address space need not be mapped.
+ *
+ * Unlike VMX (where the four PDPTEs are loaded from the VMCS when EPT is
+ * enabled), SVM always loads the PAE PDPTEs from memory at guest CR3, so
+ * a real PDPT is required even when NPT is enabled.
+ */
+extern char svm_32bit_guest_begin[];
+
+asm(".code32\n\t"
+    "svm_32bit_guest_begin:\n\t"
+    "        mov $1, %eax\n\t"
+    "        vmmcall\n\t"
+    "        mov $2, %eax\n\t"
+    "        vmmcall\n\t"
+    "1:      jmp 1b\n\t"
+    ".code64\n\t");
+
+static u64 svm_32bit_build_page_tables(void)
+{
+	const u64 leaf_flags = PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_PAGE_SIZE_MASK;
+	u32 *pd = memalign_pages_flags(PAGE_SIZE, PAGE_SIZE, AREA_DMA32);
+	int i;
+
+	for (i = 0; i < 1024; i++)
+		pd[i] = ((u32)i << 22) | leaf_flags;
+	return virt_to_phys(pd);
+}
+
+static void svm_32bit_guest_prepare_common(struct svm_test *test, u64 cr3)
+{
+	struct vmcb_save_area *save = &vmcb->save;
+
+	vmcb_ident(vmcb);
+	test->scratch = 0;
+
+	/*
+	 * 32-bit code segment attribute:
+	 *   type=B (execute/read/accessed), S=1, DPL=0, P=1,
+	 *   L=0 (32-bit), D/B=1 (32-bit operand), G=1 (4K granularity).
+	 */
+	save->cs.attrib = 0xc9b;
+
+	save->efer &= ~(EFER_LMA | EFER_LME);
+	save->cr0 |= X86_CR0_PG | X86_CR0_PE;
+	save->cr4 &= ~X86_CR4_PSE;
+	save->cr4 |= X86_CR4_PAE;
+	save->cr3 = cr3;
+	regs.rax = 0x123457678;
+}
+
+static void svm_32bit_guest_prepare(struct svm_test *test)
+{
+	u64 cr3 = svm_32bit_build_page_tables();
+
+	svm_32bit_guest_prepare_common(test, cr3);
+}
+
+static void svm_32bit_guest_prepare_gif_clear(struct svm_test *test)
+{
+	if (test->scratch == 0)
+		vmcb->save.rip = (ulong)svm_32bit_guest_begin;
+}
+
+static void svm_32bit_guest_test(struct svm_test *test)
+{
+	/* Unused: RIP is overridden in prepare_gif_clear. */
+}
+
+static bool svm_32bit_guest_finished(struct svm_test *test)
+{
+	if (vmcb->control.exit_code != SVM_EXIT_VMMCALL) {
+		report_fail("32-bit guest: unexpected exit code 0x%x",
+			    vmcb->control.exit_code);
+		return true;
+	}
+
+	vmcb->save.rip += 3;
+
+	switch (test->scratch) {
+	case 0:
+		report(vmcb->save.rax == 1, "32-bit guest first VMMCALL");
+		test->scratch = 1;
+		return false;
+	case 1:
+		report(vmcb->save.rax == 2, "32-bit guest second VMMCALL");
+		test->scratch = 2;
+		return true;
+	default:
+		report_fail("32-bit guest: unexpected stage %ld", test->scratch);
+		return true;
+	}
+}
+
+static void svm_32bit_free_page_tables(void)
+{
+	u64 cr3 = vmcb->save.cr3;
+
+	free_page(phys_to_virt(cr3));
+}
+
+static bool svm_32bit_guest_check(struct svm_test *test)
+{
+	svm_32bit_free_page_tables();
+	return test->scratch == 2;
+}
+
 extern u8 *io_bitmap;
 
 static void prepare_ioio(struct svm_test *test)
@@ -3692,6 +3803,9 @@ struct svm_test svm_tests[] = {
 	{ "vgif", vgif_supported, prepare_vgif_enabled,
 	  default_prepare_gif_clear, test_vgif, vgif_finished,
 	  vgif_check },
+	{ "32bit_guest", default_supported, svm_32bit_guest_prepare,
+	  svm_32bit_guest_prepare_gif_clear, svm_32bit_guest_test, svm_32bit_guest_finished,
+	  svm_32bit_guest_check },
 	TEST(svm_cr4_osxsave_test),
 	TEST(svm_guest_state_test),
 	TEST(svm_vmrun_errata_test),
-- 
2.54.0