x86/xen: Provide a "Xen PV" APIC driver to support >255 VCPUs

Instead of mangling the default APIC driver, provide a Xen PV guest
specific one that explicitly provides appropriate methods.

This allows use to report that all APIC IDs are valid, allowing dom0
to boot with more than 255 VCPUs.

Since the probe order of APIC drivers is link dependent, we add in an
late probe function to change to the Xen PV if it hadn't been done
during bootup.

Suggested-by: David Vrabel <david.vrabel@citrix.com>
Reported-by: Cathy Avery <cathy.avery@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>

1 files changed, 1 insertions, 89 deletions

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 5240f563076d..b9a227284149 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -927,92 +927,6 @@ static void xen_io_delay(void)
 {
 }
 
-#ifdef CONFIG_X86_LOCAL_APIC
-static unsigned long xen_set_apic_id(unsigned int x)
-{
-	WARN_ON(1);
-	return x;
-}
-static unsigned int xen_get_apic_id(unsigned long x)
-{
-	return ((x)>>24) & 0xFFu;
-}
-static u32 xen_apic_read(u32 reg)
-{
-	struct xen_platform_op op = {
-		.cmd = XENPF_get_cpuinfo,
-		.interface_version = XENPF_INTERFACE_VERSION,
-		.u.pcpu_info.xen_cpuid = 0,
-	};
-	int ret = 0;
-
-	/* Shouldn't need this as APIC is turned off for PV, and we only
-	 * get called on the bootup processor. But just in case. */
-	if (!xen_initial_domain() || smp_processor_id())
-		return 0;
-
-	if (reg == APIC_LVR)
-		return 0x10;
-
-	if (reg != APIC_ID)
-		return 0;
-
-	ret = HYPERVISOR_dom0_op(&op);
-	if (ret)
-		return 0;
-
-	return op.u.pcpu_info.apic_id << 24;
-}
-
-static void xen_apic_write(u32 reg, u32 val)
-{
-	/* Warn to see if there's any stray references */
-	WARN_ON(1);
-}
-
-static u64 xen_apic_icr_read(void)
-{
-	return 0;
-}
-
-static void xen_apic_icr_write(u32 low, u32 id)
-{
-	/* Warn to see if there's any stray references */
-	WARN_ON(1);
-}
-
-static void xen_apic_wait_icr_idle(void)
-{
-        return;
-}
-
-static u32 xen_safe_apic_wait_icr_idle(void)
-{
-        return 0;
-}
-
-static void set_xen_basic_apic_ops(void)
-{
-	apic->read = xen_apic_read;
-	apic->write = xen_apic_write;
-	apic->icr_read = xen_apic_icr_read;
-	apic->icr_write = xen_apic_icr_write;
-	apic->wait_icr_idle = xen_apic_wait_icr_idle;
-	apic->safe_wait_icr_idle = xen_safe_apic_wait_icr_idle;
-	apic->set_apic_id = xen_set_apic_id;
-	apic->get_apic_id = xen_get_apic_id;
-
-#ifdef CONFIG_SMP
-	apic->send_IPI_allbutself = xen_send_IPI_allbutself;
-	apic->send_IPI_mask_allbutself = xen_send_IPI_mask_allbutself;
-	apic->send_IPI_mask = xen_send_IPI_mask;
-	apic->send_IPI_all = xen_send_IPI_all;
-	apic->send_IPI_self = xen_send_IPI_self;
-#endif
-}
-
-#endif
-
 static void xen_clts(void)
 {
 	struct multicall_space mcs;
@@ -1618,7 +1532,7 @@ asmlinkage __visible void __init xen_start_kernel(void)
 	/*
 	 * set up the basic apic ops.
 	 */
-	set_xen_basic_apic_ops();
+	xen_init_apic();
 #endif
 
 	if (xen_feature(XENFEAT_mmu_pt_update_preserve_ad)) {
@@ -1731,8 +1645,6 @@ asmlinkage __visible void __init xen_start_kernel(void)
 		if (HYPERVISOR_dom0_op(&op) == 0)
 			boot_params.kbd_status = op.u.firmware_info.u.kbd_shift_flags;
 
-		xen_init_apic();
-
 		/* Make sure ACS will be enabled */
 		pci_request_acs();