diff options
| author | Vitaly Kuznetsov <vkuznets@redhat.com> | 2016-06-30 17:56:37 +0200 |
|---|---|---|
| committer | David Vrabel <david.vrabel@citrix.com> | 2016-07-25 13:31:16 +0100 |
| commit | 88e957d6e47f1232ad15b21e54a44f1147ea8c1b (patch) | |
| tree | e7384643d570bd17463455d26fc63ada4ecf24a4 /arch/x86 | |
| parent | 3e9e57fad3d8530aa30787f861c710f598ddc4e7 (diff) | |
xen: introduce xen_vcpu_id mapping
It may happen that Xen's and Linux's ideas of vCPU id diverge. In
particular, when we crash on a secondary vCPU we may want to do kdump
and unlike plain kexec where we do migrate_to_reboot_cpu() we try
booting on the vCPU which crashed. This doesn't work very well for
PVHVM guests as we have a number of hypercalls where we pass vCPU id
as a parameter. These hypercalls either fail or do something
unexpected.
To solve the issue introduce percpu xen_vcpu_id mapping. ARM and PV
guests get direct mapping for now. Boot CPU for PVHVM guest gets its
id from CPUID. With secondary CPUs it is a bit more
trickier. Currently, we initialize IPI vectors before these CPUs boot
so we can't use CPUID. Use ACPI ids from MADT instead.
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/xen/enlighten.c | 23 |
1 files changed, 22 insertions, 1 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index ee7d71ec762f..d093949c94e0 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -59,6 +59,7 @@ #include <asm/xen/pci.h> #include <asm/xen/hypercall.h> #include <asm/xen/hypervisor.h> +#include <asm/xen/cpuid.h> #include <asm/fixmap.h> #include <asm/processor.h> #include <asm/proto.h> @@ -118,6 +119,10 @@ DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu); */ DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info); +/* Linux <-> Xen vCPU id mapping */ +DEFINE_PER_CPU(int, xen_vcpu_id) = -1; +EXPORT_PER_CPU_SYMBOL(xen_vcpu_id); + enum xen_domain_type xen_domain_type = XEN_NATIVE; EXPORT_SYMBOL_GPL(xen_domain_type); @@ -1137,8 +1142,11 @@ void xen_setup_vcpu_info_placement(void) { int cpu; - for_each_possible_cpu(cpu) + for_each_possible_cpu(cpu) { + /* Set up direct vCPU id mapping for PV guests. */ + per_cpu(xen_vcpu_id, cpu) = cpu; xen_vcpu_setup(cpu); + } /* xen_vcpu_setup managed to place the vcpu_info within the * percpu area for all cpus, so make use of it. Note that for @@ -1729,6 +1737,9 @@ asmlinkage __visible void __init xen_start_kernel(void) #endif xen_raw_console_write("about to get started...\n"); + /* Let's presume PV guests always boot on vCPU with id 0. */ + per_cpu(xen_vcpu_id, 0) = 0; + xen_setup_runstate_info(0); xen_efi_init(); @@ -1797,6 +1808,12 @@ static void __init init_hvm_pv_info(void) xen_setup_features(); + cpuid(base + 4, &eax, &ebx, &ecx, &edx); + if (eax & XEN_HVM_CPUID_VCPU_ID_PRESENT) + this_cpu_write(xen_vcpu_id, ebx); + else + this_cpu_write(xen_vcpu_id, smp_processor_id()); + pv_info.name = "Xen HVM"; xen_domain_type = XEN_HVM_DOMAIN; @@ -1808,6 +1825,10 @@ static int xen_hvm_cpu_notify(struct notifier_block *self, unsigned long action, int cpu = (long)hcpu; switch (action) { case CPU_UP_PREPARE: + if (cpu_acpi_id(cpu) != U32_MAX) + per_cpu(xen_vcpu_id, cpu) = cpu_acpi_id(cpu); + else + per_cpu(xen_vcpu_id, cpu) = cpu; xen_vcpu_setup(cpu); if (xen_have_vector_callback) { if (xen_feature(XENFEAT_hvm_safe_pvclock)) |