[kvm-unit-tests PATCH 3/3] x86: Support environments without test-devices

[Nadav Amit <nadav.amit@gmail.com>]

Enable to run the tests when test-device is not present (e.g.,
bare-metal). Users can provide the number of CPUs and ram size through
kernel parameters.

On Ubuntu, for example, the tests can be run by copying a test to the
boot directory (/boot) and adding a menuentry to grub (editing
/etc/grub.d/40_custom):

  menuentry 'idt_test' {
	set root='ROOT'
	multiboot BOOT_RELATIVE/idt_test.flat ignore nb_cpus=48 \
		ram_size=4294967296 no-test-device
  }

Replace ROOT with `grub-probe --target=bios_hints /boot` and
BOOT_RELATIVE with `grub-mkrelpath /boot`, and run update-grub.

Note that the first kernel parameter is ignored for compatibility with
test executions through QEMU.

Remember that the output goes to the serial port.

Signed-off-by: Nadav Amit <nadav.amit@gmail.com>
---
 lib/x86/fwcfg.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++
 lib/x86/fwcfg.h |  4 ++++
 x86/apic.c      |  4 +++-
 x86/cstart64.S  | 13 ++++++++---
 x86/eventinj.c  | 20 ++++++++++++----
 x86/vmx_tests.c |  7 ++++++
 6 files changed, 102 insertions(+), 8 deletions(-)

diff --git a/lib/x86/fwcfg.c b/lib/x86/fwcfg.c
index c52b445..8d320e2 100644
--- a/lib/x86/fwcfg.c
+++ b/lib/x86/fwcfg.c
@@ -1,14 +1,76 @@
 #include "fwcfg.h"
 #include "smp.h"
+#include "libcflat.h"
 
 static struct spinlock lock;
 
+struct fw_override_val {
+	bool initialized;
+	uint64_t val;
+};
+
+static struct fw_override_val fw_override[FW_CFG_MAX_ENTRY];
+
+static const char *cfg_names[FW_CFG_MAX_ENTRY] = {
+	[FW_CFG_NB_CPUS] = "nb_cpus",
+	[FW_CFG_RAM_SIZE] = "ram_size",
+};
+
+bool no_test_device;
+
+void read_cfg_override(int argc, const char *argv[])
+{
+	int i, j;
+
+	/* Check if there is no test device */
+	for (j = 0; j < argc; j++) {
+		const char *arg = argv[j];
+
+		if (!strcmp("no-test-device", arg)) {
+			no_test_device = true;
+			continue;
+		}
+
+		for (i = 0; i < FW_CFG_MAX_ENTRY; i++) {
+			const char *cfg_name = cfg_names[i];
+			size_t name_len;
+
+			name_len = strlen(cfg_name);
+
+			if (cfg_name == NULL)
+				continue;
+
+			name_len = strlen(cfg_name);
+
+			if (strncmp(cfg_name, arg, name_len))
+				continue;
+			if (arg[name_len] != '=')
+				continue;
+			if (strlen(arg) <= name_len + 1)
+				continue;
+
+			fw_override[i].val = atol(arg + name_len + 1);
+			fw_override[i].initialized = true;
+
+			printf("cfg-override: %s = 0x%lx\n", cfg_name, fw_override[i].val);
+		}
+	}
+}
+
+bool test_device_enabled(void)
+{
+	return !no_test_device;
+}
+
 static uint64_t fwcfg_get_u(uint16_t index, int bytes)
 {
     uint64_t r = 0;
     uint8_t b;
     int i;
 
+    if (fw_override[index].initialized)
+	    return fw_override[index].val;
+
     spin_lock(&lock);
     asm volatile ("out %0, %1" : : "a"(index), "d"((uint16_t)BIOS_CFG_IOPORT));
     for (i = 0; i < bytes; ++i) {
diff --git a/lib/x86/fwcfg.h b/lib/x86/fwcfg.h
index e0836ca..14801d7 100644
--- a/lib/x86/fwcfg.h
+++ b/lib/x86/fwcfg.h
@@ -2,6 +2,7 @@
 #define FWCFG_H
 
 #include <stdint.h>
+#include <stdbool.h>
 
 #define FW_CFG_SIGNATURE        0x00
 #define FW_CFG_ID               0x01
@@ -33,6 +34,9 @@
 #define FW_CFG_SMBIOS_ENTRIES (FW_CFG_ARCH_LOCAL + 1)
 #define FW_CFG_IRQ0_OVERRIDE (FW_CFG_ARCH_LOCAL + 2)
 
+void read_cfg_override(int argc, const char *argv[]);
+bool test_device_enabled(void);
+
 uint8_t fwcfg_get_u8(unsigned index);
 uint16_t fwcfg_get_u16(unsigned index);
 uint32_t fwcfg_get_u32(unsigned index);
diff --git a/x86/apic.c b/x86/apic.c
index 7617351..f01a5e7 100644
--- a/x86/apic.c
+++ b/x86/apic.c
@@ -6,6 +6,7 @@
 #include "isr.h"
 #include "msr.h"
 #include "atomic.h"
+#include "fwcfg.h"
 
 #define MAX_TPR			0xf
 
@@ -655,7 +656,8 @@ int main(void)
 
     test_self_ipi();
     test_physical_broadcast();
-    test_pv_ipi();
+    if (test_device_enabled())
+        test_pv_ipi();
 
     test_sti_nmi();
     test_multiple_nmi();
diff --git a/x86/cstart64.S b/x86/cstart64.S
index 9d89887..cc7926a 100644
--- a/x86/cstart64.S
+++ b/x86/cstart64.S
@@ -244,9 +244,6 @@ start64:
 	call load_tss
 	call mask_pic_interrupts
 	call enable_apic
-	call save_id
-	call smp_init
-	call enable_x2apic
 	mov mb_boot_info(%rip), %rbx
 	mov %rbx, %rdi
 	call setup_multiboot
@@ -254,6 +251,16 @@ start64:
 	mov mb_cmdline(%rbx), %eax
 	mov %rax, __args(%rip)
 	call __setup_args
+
+	/* read configuration override */
+	mov __argc(%rip), %edi
+	lea __argv(%rip), %rsi
+	call read_cfg_override
+
+	call save_id
+	call smp_init
+	call enable_x2apic
+
 	mov __argc(%rip), %edi
 	lea __argv(%rip), %rsi
 	lea __environ(%rip), %rdx
diff --git a/x86/eventinj.c b/x86/eventinj.c
index 901b9db..9e4dbec 100644
--- a/x86/eventinj.c
+++ b/x86/eventinj.c
@@ -8,6 +8,7 @@
 #include "vmalloc.h"
 #include "alloc_page.h"
 #include "delay.h"
+#include "fwcfg.h"
 
 #ifdef __x86_64__
 #  define R "r"
@@ -28,10 +29,15 @@ static void apic_self_nmi(void)
 	apic_icr_write(APIC_DEST_PHYSICAL | APIC_DM_NMI | APIC_INT_ASSERT, 0);
 }
 
-#define flush_phys_addr(__s) outl(__s, 0xe4)
+#define flush_phys_addr(__s) do {					\
+		if (test_device_enabled())				\
+			outl(__s, 0xe4);				\
+	} while (0)
+
 #define flush_stack() do {						\
 		int __l;						\
-		flush_phys_addr(virt_to_phys(&__l));			\
+		if (test_device_enabled())				\
+			flush_phys_addr(virt_to_phys(&__l));		\
 	} while (0)
 
 extern char isr_iret_ip[];
@@ -136,6 +142,8 @@ extern void do_iret(ulong phys_stack, void *virt_stack);
 // Return to same privilege level won't pop SS or SP, so
 // save it in RDX while we run on the nested stack
 
+extern bool no_test_device;
+
 asm("do_iret:"
 #ifdef __x86_64__
 	"mov %rdi, %rax \n\t"		// phys_stack
@@ -148,10 +156,14 @@ asm("do_iret:"
 	"pushf"W" \n\t"
 	"mov %cs, %ecx \n\t"
 	"push"W" %"R "cx \n\t"
-	"push"W" $1f \n\t"
+	"push"W" $2f \n\t"
+
+	"cmpb $0, no_test_device\n\t"	// see if need to flush
+	"jnz 1f\n\t"
 	"outl %eax, $0xe4 \n\t"		// flush page
+	"1: \n\t"
 	"iret"W" \n\t"
-	"1: xchg %"R "dx, %"R "sp \n\t"	// point to old stack
+	"2: xchg %"R "dx, %"R "sp \n\t"	// point to old stack
 	"ret\n\t"
    );
 
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index c51de1c..5709fa8 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -8017,6 +8017,13 @@ static void vmx_apic_passthrough(bool set_irq_line_from_thread)
 		return;
 	}
 
+	/*
+	 * Test device required for generating IRQs
+	 */
+	if (!test_device_enabled()) {
+		report_skip(__func__);
+		return;
+	}
 	u64 cpu_ctrl_0 = CPU_SECONDARY;
 	u64 cpu_ctrl_1 = 0;
 
-- 
2.17.1