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| author | David Vrabel <david.vrabel@citrix.com> | 2012-02-02 15:28:58 +0000 |
|---|---|---|
| committer | David Vrabel <david.vrabel@citrix.com> | 2012-02-02 15:28:58 +0000 |
| commit | 7d44891ccc13b842b9f135c77233d4d56720e219 (patch) | |
| tree | 2a9572399a1aa050dfa3e076b7f7f2b6f74b8572 /xen/arch/x86/traps.c | |
| parent | a6b64c00c491c5e563e90bda35b2e4ccc02edb94 (diff) | |
| download | xen-7d44891ccc13b842b9f135c77233d4d56720e219.tar.gz xen-7d44891ccc13b842b9f135c77233d4d56720e219.tar.bz2 xen-7d44891ccc13b842b9f135c77233d4d56720e219.zip | |
x86: avoid deadlock after a PCI SERR NMI
If a PCI System Error (SERR) is asserted it causes an NMI. If this NMI
occurs while the CPU is in printk() then Xen may deadlock as
pci_serr_error() calls console_force_unlock() which screws up the
console lock.
printk() isn't safe to call from NMI context so defer the diagnostic
message to a softirq.
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Tested-by: George Dunlap <george.dunlap@eu.citrix.com>
Committed-by: Keir Fraser <keir@xen.org>
Diffstat (limited to 'xen/arch/x86/traps.c')
| -rw-r--r-- | xen/arch/x86/traps.c | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c index 2057ac5c2e..286f1a2954 100644 --- a/xen/arch/x86/traps.c +++ b/xen/arch/x86/traps.c @@ -3173,6 +3173,11 @@ static void nmi_mce_softirq(void) st->vcpu = NULL; } +static void pci_serr_softirq(void) +{ + printk("\n\nNMI - PCI system error (SERR)\n"); +} + void async_exception_cleanup(struct vcpu *curr) { int trap; @@ -3259,10 +3264,11 @@ static void nmi_dom0_report(unsigned int reason_idx) static void pci_serr_error(struct cpu_user_regs *regs) { - console_force_unlock(); - printk("\n\nNMI - PCI system error (SERR)\n"); - outb((inb(0x61) & 0x0f) | 0x04, 0x61); /* clear-and-disable the PCI SERR error line. */ + + /* Would like to print a diagnostic here but can't call printk() + from NMI context -- raise a softirq instead. */ + raise_softirq(PCI_SERR_SOFTIRQ); } static void io_check_error(struct cpu_user_regs *regs) @@ -3563,6 +3569,7 @@ void __init trap_init(void) cpu_init(); open_softirq(NMI_MCE_SOFTIRQ, nmi_mce_softirq); + open_softirq(PCI_SERR_SOFTIRQ, pci_serr_softirq); } long register_guest_nmi_callback(unsigned long address) |