x86/xen: implement early init hook

Unify the HVM and PVH early setup, byt making both rely on the hypervisor
initialization hook part of identify_hypervisor().

The current initialization takes care of the hypercall page, the sahred info
page and does any fixup necessary to metadata video console information if
FreeBSD is booted as the initial domain (so the video console is handed from
Xen into FreeBSD).

Note this has the nice side effect of also allowing to use the Xen console on
HVM guests, which allows to get rid of the QEMU emulated uart and still get
a nice text console.

Sponsored by: Cloud Software Group
Reviewed by: markj
Differential revision: https://reviews.freebsd.org/D43764

4 files changed, 22 insertions, 112 deletions

diff --git a/sys/x86/include/xen/xen-os.h b/sys/x86/include/xen/xen-os.h
index ec0d4b1ab9f1..d3f21e2a6c45 100644
--- a/sys/x86/include/xen/xen-os.h
+++ b/sys/x86/include/xen/xen-os.h
@@ -52,8 +52,6 @@ extern int xen_disable_pv_disks;
 /* tunable for disabling PV nics */
 extern int xen_disable_pv_nics;
 
-extern uint32_t xen_cpuid_base;
-
 /* compatibility for accessing xen_ulong_t with atomics */
 #define	atomic_clear_xen_ulong		atomic_clear_long
 #define	atomic_set_xen_ulong		atomic_set_long
diff --git a/sys/x86/x86/identcpu.c b/sys/x86/x86/identcpu.c
index 6df138bccba1..919dda722d71 100644
--- a/sys/x86/x86/identcpu.c
+++ b/sys/x86/x86/identcpu.c
@@ -67,6 +67,10 @@
 #include <x86/isa/icu.h>
 #include <x86/vmware.h>
 
+#ifdef XENHVM
+#include <xen/xen-os.h>
+#endif
+
 #ifdef __i386__
 #define	IDENTBLUE_CYRIX486	0
 #define	IDENTBLUE_IBMCPU	1
@@ -1345,7 +1349,11 @@ static struct {
 	int		vm_guest;
 	void		(*init)(void);
 } vm_cpuids[] = {
-	{ "XenVMMXenVMM",	VM_GUEST_XEN },		/* XEN */
+	{ "XenVMMXenVMM",	VM_GUEST_XEN,
+#ifdef XENHVM
+	  &xen_early_init,
+#endif
+	},						/* XEN */
 	{ "Microsoft Hv",	VM_GUEST_HV },		/* Microsoft Hyper-V */
 	{ "VMwareVMware",	VM_GUEST_VMWARE },	/* VMware VM */
 	{ "KVMKVMKVM",		VM_GUEST_KVM },		/* KVM */
diff --git a/sys/x86/xen/hvm.c b/sys/x86/xen/hvm.c
index 6336602c8bc4..17500516debf 100644
--- a/sys/x86/xen/hvm.c
+++ b/sys/x86/xen/hvm.c
@@ -104,22 +104,6 @@ void xen_emergency_print(const char *str, size_t size)
 	outsb(XEN_HVM_DEBUGCONS_IOPORT, str, size);
 }
 
-uint32_t xen_cpuid_base;
-
-static uint32_t
-xen_hvm_cpuid_base(void)
-{
-	uint32_t base, regs[4];
-
-	for (base = 0x40000000; base < 0x40010000; base += 0x100) {
-		do_cpuid(base, regs);
-		if (!memcmp("XenVMMXenVMM", &regs[1], 12)
-		    && (regs[0] - base) >= 2)
-			return (base);
-	}
-	return (0);
-}
-
 static void
 hypervisor_quirks(unsigned int major, unsigned int minor)
 {
@@ -157,38 +141,6 @@ hypervisor_version(void)
 }
 
 /*
- * Allocate and fill in the hypcall page.
- */
-int
-xen_hvm_init_hypercall_stubs(enum xen_hvm_init_type init_type)
-{
-	uint32_t regs[4];
-
-	if (xen_cpuid_base != 0)
-		/* Already setup. */
-		goto out;
-
-	xen_cpuid_base = xen_hvm_cpuid_base();
-	if (xen_cpuid_base == 0)
-		return (ENXIO);
-
-	/*
-	 * Find the hypercall pages.
-	 */
-	do_cpuid(xen_cpuid_base + 2, regs);
-	if (regs[0] != 1)
-		return (EINVAL);
-
-	wrmsr(regs[1], (init_type == XEN_HVM_INIT_EARLY)
-	    ? (vm_paddr_t)((uintptr_t)&hypercall_page - KERNBASE)
-	    : vtophys(&hypercall_page));
-
-out:
-	hypervisor_version();
-	return (0);
-}
-
-/*
  * Translate linear to physical address when still running on the bootloader
  * created page-tables.
  */
@@ -336,12 +288,14 @@ xen_early_init(void)
 	uint32_t regs[4];
 	int rc;
 
-	xen_cpuid_base = xen_hvm_cpuid_base();
-	if (xen_cpuid_base == 0)
+	if (hv_high < hv_base + 2) {
+		xc_printf("Invalid maximum leaves for hv_base\n");
+		vm_guest = VM_GUEST_VM;
 		return;
+	}
 
 	/* Find the hypercall pages. */
-	do_cpuid(xen_cpuid_base + 2, regs);
+	do_cpuid(hv_base + 2, regs);
 	if (regs[0] != 1) {
 		xc_printf("Invalid number of hypercall pages %u\n",
 		    regs[0]);
@@ -362,33 +316,6 @@ xen_early_init(void)
 	    fixup_console();
 }
 
-static void
-xen_hvm_init_shared_info_page(void)
-{
-	struct xen_add_to_physmap xatp;
-
-	if (xen_pv_domain()) {
-		/*
-		 * Already setup in the PV case, shared_info is passed inside
-		 * of the start_info struct at start of day.
-		 */
-		return;
-	}
-
-	if (HYPERVISOR_shared_info == NULL) {
-		HYPERVISOR_shared_info = malloc(PAGE_SIZE, M_XENHVM, M_NOWAIT);
-		if (HYPERVISOR_shared_info == NULL)
-			panic("Unable to allocate Xen shared info page");
-	}
-
-	xatp.domid = DOMID_SELF;
-	xatp.idx = 0;
-	xatp.space = XENMAPSPACE_shared_info;
-	xatp.gpfn = vtophys(HYPERVISOR_shared_info) >> PAGE_SHIFT;
-	if (HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp))
-		panic("HYPERVISOR_memory_op failed");
-}
-
 static int
 set_percpu_callback(unsigned int vcpu)
 {
@@ -505,32 +432,29 @@ xen_hvm_disable_emulated_devices(void)
 static void
 xen_hvm_init(enum xen_hvm_init_type init_type)
 {
-	int error;
-	int i;
+	unsigned int i;
 
 	if (!xen_domain() ||
 	    init_type == XEN_HVM_INIT_CANCELLED_SUSPEND)
 		return;
 
-	error = xen_hvm_init_hypercall_stubs(init_type);
+	hypervisor_version();
 
 	switch (init_type) {
 	case XEN_HVM_INIT_LATE:
-		if (error != 0)
-			return;
-
 		setup_xen_features();
 #ifdef SMP
 		cpu_ops = xen_hvm_cpu_ops;
 #endif
 		break;
 	case XEN_HVM_INIT_RESUME:
-		if (error != 0)
-			panic("Unable to init Xen hypercall stubs on resume");
-
 		/* Clear stale vcpu_info. */
 		CPU_FOREACH(i)
 			DPCPU_ID_SET(i, vcpu_info, NULL);
+
+		if (map_shared_info() != 0)
+			panic("cannot map Xen shared info page");
+
 		break;
 	default:
 		panic("Unsupported HVM initialization type");
@@ -540,13 +464,6 @@ xen_hvm_init(enum xen_hvm_init_type init_type)
 	xen_evtchn_needs_ack = false;
 	xen_hvm_set_callback(NULL);
 
-	/*
-	 * On (PV)HVM domains we need to request the hypervisor to
-	 * fill the shared info page, for PVH guest the shared_info page
-	 * is passed inside the start_info struct and is already set, so this
-	 * functions are no-ops.
-	 */
-	xen_hvm_init_shared_info_page();
 	xen_hvm_disable_emulated_devices();
 } 
 
diff --git a/sys/x86/xen/pv.c b/sys/x86/xen/pv.c
index e33fa41c83d7..0e6492b124b8 100644
--- a/sys/x86/xen/pv.c
+++ b/sys/x86/xen/pv.c
@@ -147,12 +147,9 @@ isxen(void)
 }
 
 #define CRASH(...) do {					\
-	if (isxen()) {					\
+	if (isxen())					\
 		xc_printf(__VA_ARGS__);			\
-		HYPERVISOR_shutdown(SHUTDOWN_crash);	\
-	} else {					\
-		halt();					\
-	}						\
+	halt();						\
 } while (0)
 
 uint64_t
@@ -162,16 +159,6 @@ hammer_time_xen(vm_paddr_t start_info_paddr)
 	uint64_t physfree;
 	char *kenv;
 
-	if (isxen()) {
-		vm_guest = VM_GUEST_XEN;
-		xen_early_init();
-		if (xen_cpuid_base == 0) {
-			xc_printf(
-			    "ERROR: failed to initialize hypercall page\n");
-			HYPERVISOR_shutdown(SHUTDOWN_crash);
-		}
-	}
-
 	start_info = (struct hvm_start_info *)(start_info_paddr + KERNBASE);
 	if (start_info->magic != XEN_HVM_START_MAGIC_VALUE) {
 		CRASH("Unknown magic value in start_info struct: %#x\n",