xen: Support 64-bit PV guest receiving NMIs

This is based on a patch that Zhenzhong Duan had sent - which
was missing some of the remaining pieces. The kernel has the
logic to handle Xen-type-exceptions using the paravirt interface
in the assembler code (see PARAVIRT_ADJUST_EXCEPTION_FRAME -
pv_irq_ops.adjust_exception_frame and and INTERRUPT_RETURN -
pv_cpu_ops.iret).

That means the nmi handler (and other exception handlers) use
the hypervisor iret.

The other changes that would be neccessary for this would
be to translate the NMI_VECTOR to one of the entries on the
ipi_vector and make xen_send_IPI_mask_allbutself use different
events.

Fortunately for us commit 1db01b4903639fcfaec213701a494fe3fb2c490b
(xen: Clean up apic ipi interface) implemented this and we piggyback
on the cleanup such that the apic IPI interface will pass the right
vector value for NMI.

With this patch we can trigger NMIs within a PV guest (only tested
x86_64).

For this to work with normal PV guests (not initial domain)
we need the domain to be able to use the APIC ops - they are
already implemented to use the Xen event channels. For that
to be turned on in a PV domU we need to remove the masking
of X86_FEATURE_APIC.

Incidentally that means kgdb will also now work within
a PV guest without using the 'nokgdbroundup' workaround.

Note that the 32-bit version is different and this patch
does not enable that.

CC: Lisa Nguyen <lisa@xenapiadmin.com>
CC: Ben Guthro <benjamin.guthro@citrix.com>
CC: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
[v1: Fixed up per David Vrabel comments]
Reviewed-by: Ben Guthro <benjamin.guthro@citrix.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>

diff --git a/arch/x86/include/asm/xen/events.h b/arch/x86/include/asm/xen/events.h
index ca842f2769efa1545951f52647b34a7e6c051c7f..608a79d5a4669ebf3a9060f895d0f5f03ab3286c 100644 (file)
--- a/arch/x86/include/asm/xen/events.h
+++ b/arch/x86/include/asm/xen/events.h
@@ -7,6 +7,7 @@ enum ipi_vector {
        XEN_CALL_FUNCTION_SINGLE_VECTOR,
        XEN_SPIN_UNLOCK_VECTOR,
        XEN_IRQ_WORK_VECTOR,
+       XEN_NMI_VECTOR,
 
        XEN_NR_IPIS,
 };

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 193097ef3d7d0d886ffa88b6c735571b9f66c1ec..b5a22fa7e249989584691d80f6c051423d455b07 100644 (file)
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -427,8 +427,7 @@ static void __init xen_init_cpuid_mask(void)
 
        if (!xen_initial_domain())
                cpuid_leaf1_edx_mask &=
-                       ~((1 << X86_FEATURE_APIC) |  /* disable local APIC */
-                         (1 << X86_FEATURE_ACPI));  /* disable ACPI */
+                       ~((1 << X86_FEATURE_ACPI));  /* disable ACPI */
 
        cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_X2APIC % 32));
 
@@ -735,8 +734,7 @@ static int cvt_gate_to_trap(int vector, const gate_desc *val,
                addr = (unsigned long)xen_int3;
        else if (addr == (unsigned long)stack_segment)
                addr = (unsigned long)xen_stack_segment;
-       else if (addr == (unsigned long)double_fault ||
-                addr == (unsigned long)nmi) {
+       else if (addr == (unsigned long)double_fault) {
                /* Don't need to handle these */
                return 0;
 #ifdef CONFIG_X86_MCE
@@ -747,7 +745,12 @@ static int cvt_gate_to_trap(int vector, const gate_desc *val,
                 */
                ;
 #endif
-       } else {
+       } else if (addr == (unsigned long)nmi)
+               /*
+                * Use the native version as well.
+                */
+               ;
+       else {
                /* Some other trap using IST? */
                if (WARN_ON(val->ist != 0))
                        return 0;

diff --git a/arch/x86/xen/setup.c b/arch/x86/xen/setup.c
index 056d11faef21e96e5adf56a455a2827d2f97fbf1..403f5cc5415beb68d92aec9036e0220205768c27 100644 (file)
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -33,6 +33,9 @@
 /* These are code, but not functions.  Defined in entry.S */
 extern const char xen_hypervisor_callback[];
 extern const char xen_failsafe_callback[];
+#ifdef CONFIG_X86_64
+extern const char nmi[];
+#endif
 extern void xen_sysenter_target(void);
 extern void xen_syscall_target(void);
 extern void xen_syscall32_target(void);
@@ -525,7 +528,13 @@ void xen_enable_syscall(void)
        }
 #endif /* CONFIG_X86_64 */
 }
-
+void __cpuinit xen_enable_nmi(void)
+{
+#ifdef CONFIG_X86_64
+       if (register_callback(CALLBACKTYPE_nmi, nmi))
+               BUG();
+#endif
+}
 void __init xen_arch_setup(void)
 {
        xen_panic_handler_init();
@@ -543,7 +552,7 @@ void __init xen_arch_setup(void)
 
        xen_enable_sysenter();
        xen_enable_syscall();
-
+       xen_enable_nmi();
 #ifdef CONFIG_ACPI
        if (!(xen_start_info->flags & SIF_INITDOMAIN)) {
                printk(KERN_INFO "ACPI in unprivileged domain disabled\n");

diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index ca92754eb846b6d7f8293a4f6f75dedae7bf13a9..22759c6d309f0951d08b6537a22cab58fe9afe04 100644 (file)
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -572,6 +572,12 @@ static inline int xen_map_vector(int vector)
        case IRQ_WORK_VECTOR:
                xen_vector = XEN_IRQ_WORK_VECTOR;
                break;
+#ifdef CONFIG_X86_64
+       case NMI_VECTOR:
+       case APIC_DM_NMI: /* Some use that instead of NMI_VECTOR */
+               xen_vector = XEN_NMI_VECTOR;
+               break;
+#endif
        default:
                xen_vector = -1;
                printk(KERN_ERR "xen: vector 0x%x is not implemented\n",

diff --git a/drivers/xen/events.c b/drivers/xen/events.c
index a58ac435a9a4a03f39274f8b5a41ea659d44eee7..c8b9d9fc77b5fa38c3731967ed798ca09e820724 100644 (file)
--- a/drivers/xen/events.c
+++ b/drivers/xen/events.c
@@ -56,6 +56,7 @@
 #include <xen/interface/hvm/params.h>
 #include <xen/interface/physdev.h>
 #include <xen/interface/sched.h>
+#include <xen/interface/vcpu.h>
 #include <asm/hw_irq.h>
 
 /*
@@ -1212,7 +1213,15 @@ EXPORT_SYMBOL_GPL(evtchn_put);
 
 void xen_send_IPI_one(unsigned int cpu, enum ipi_vector vector)
 {
-       int irq = per_cpu(ipi_to_irq, cpu)[vector];
+       int irq;
+
+       if (unlikely(vector == XEN_NMI_VECTOR)) {
+               int rc =  HYPERVISOR_vcpu_op(VCPUOP_send_nmi, cpu, NULL);
+               if (rc < 0)
+                       printk(KERN_WARNING "Sending nmi to CPU%d failed (rc:%d)\n", cpu, rc);
+               return;
+       }
+       irq = per_cpu(ipi_to_irq, cpu)[vector];
        BUG_ON(irq < 0);
        notify_remote_via_irq(irq);
 }

diff --git a/include/xen/interface/vcpu.h b/include/xen/interface/vcpu.h
index 87e6f8a4866198d022930a2af17db0e23153a7b6..b05288ce3991bd8ce5b0caf632cb86a81a3c59cf 100644 (file)
--- a/include/xen/interface/vcpu.h
+++ b/include/xen/interface/vcpu.h
@@ -170,4 +170,6 @@ struct vcpu_register_vcpu_info {
 };
 DEFINE_GUEST_HANDLE_STRUCT(vcpu_register_vcpu_info);
 
+/* Send an NMI to the specified VCPU. @extra_arg == NULL. */
+#define VCPUOP_send_nmi             11
 #endif /* __XEN_PUBLIC_VCPU_H__ */