From: Juergen Gross jgross@suse.com
[ Upstream commit 42b3a4cb5609de757f5445fcad18945ba9239a07 ]
Add early interrupt handlers activated by idt_setup_early_handler() to the handlers supported by Xen pv guests. This will allow for early WARN() calls not crashing the guest.
Suggested-by: Andy Lutomirski luto@kernel.org Signed-off-by: Juergen Gross jgross@suse.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Cc: xen-devel@lists.xenproject.org Cc: boris.ostrovsky@oracle.com Link: https://lkml.kernel.org/r/20171124084221.30172-1-jgross@suse.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- arch/x86/include/asm/segment.h | 12 ++++++++++++ arch/x86/mm/extable.c | 4 +++- arch/x86/xen/enlighten_pv.c | 37 ++++++++++++++++++++++++------------- arch/x86/xen/xen-asm_64.S | 14 ++++++++++++++ 4 files changed, 53 insertions(+), 14 deletions(-)
diff --git a/arch/x86/include/asm/segment.h b/arch/x86/include/asm/segment.h index b20f9d623f9c..8f09012b92e7 100644 --- a/arch/x86/include/asm/segment.h +++ b/arch/x86/include/asm/segment.h @@ -236,11 +236,23 @@ */ #define EARLY_IDT_HANDLER_SIZE 9
+/* + * xen_early_idt_handler_array is for Xen pv guests: for each entry in + * early_idt_handler_array it contains a prequel in the form of + * pop %rcx; pop %r11; jmp early_idt_handler_array[i]; summing up to + * max 8 bytes. + */ +#define XEN_EARLY_IDT_HANDLER_SIZE 8 + #ifndef __ASSEMBLY__
extern const char early_idt_handler_array[NUM_EXCEPTION_VECTORS][EARLY_IDT_HANDLER_SIZE]; extern void early_ignore_irq(void);
+#if defined(CONFIG_X86_64) && defined(CONFIG_XEN_PV) +extern const char xen_early_idt_handler_array[NUM_EXCEPTION_VECTORS][XEN_EARLY_IDT_HANDLER_SIZE]; +#endif + /* * Load a segment. Fall back on loading the zero segment if something goes * wrong. This variant assumes that loading zero fully clears the segment. diff --git a/arch/x86/mm/extable.c b/arch/x86/mm/extable.c index 30bc4812ceb8..9fe656c42aa5 100644 --- a/arch/x86/mm/extable.c +++ b/arch/x86/mm/extable.c @@ -1,6 +1,7 @@ #include <linux/extable.h> #include <linux/uaccess.h> #include <linux/sched/debug.h> +#include <xen/xen.h>
#include <asm/fpu/internal.h> #include <asm/traps.h> @@ -212,8 +213,9 @@ void __init early_fixup_exception(struct pt_regs *regs, int trapnr) * Old CPUs leave the high bits of CS on the stack * undefined. I'm not sure which CPUs do this, but at least * the 486 DX works this way. + * Xen pv domains are not using the default __KERNEL_CS. */ - if (regs->cs != __KERNEL_CS) + if (!xen_pv_domain() && regs->cs != __KERNEL_CS) goto fail;
/* diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index ae3a071e1d0f..899a22a02e95 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -622,7 +622,7 @@ static struct trap_array_entry trap_array[] = { { simd_coprocessor_error, xen_simd_coprocessor_error, false }, };
-static bool get_trap_addr(void **addr, unsigned int ist) +static bool __ref get_trap_addr(void **addr, unsigned int ist) { unsigned int nr; bool ist_okay = false; @@ -644,6 +644,14 @@ static bool get_trap_addr(void **addr, unsigned int ist) } }
+ if (nr == ARRAY_SIZE(trap_array) && + *addr >= (void *)early_idt_handler_array[0] && + *addr < (void *)early_idt_handler_array[NUM_EXCEPTION_VECTORS]) { + nr = (*addr - (void *)early_idt_handler_array[0]) / + EARLY_IDT_HANDLER_SIZE; + *addr = (void *)xen_early_idt_handler_array[nr]; + } + if (WARN_ON(ist != 0 && !ist_okay)) return false;
@@ -1261,6 +1269,21 @@ asmlinkage __visible void __init xen_start_kernel(void) xen_setup_gdt(0);
xen_init_irq_ops(); + + /* Let's presume PV guests always boot on vCPU with id 0. */ + per_cpu(xen_vcpu_id, 0) = 0; + + /* + * Setup xen_vcpu early because idt_setup_early_handler needs it for + * local_irq_disable(), irqs_disabled(). + * + * Don't do the full vcpu_info placement stuff until we have + * the cpu_possible_mask and a non-dummy shared_info. + */ + xen_vcpu_info_reset(0); + + idt_setup_early_handler(); + xen_init_capabilities();
#ifdef CONFIG_X86_LOCAL_APIC @@ -1294,18 +1317,6 @@ asmlinkage __visible void __init xen_start_kernel(void) */ acpi_numa = -1; #endif - /* Let's presume PV guests always boot on vCPU with id 0. */ - per_cpu(xen_vcpu_id, 0) = 0; - - /* - * Setup xen_vcpu early because start_kernel needs it for - * local_irq_disable(), irqs_disabled(). - * - * Don't do the full vcpu_info placement stuff until we have - * the cpu_possible_mask and a non-dummy shared_info. - */ - xen_vcpu_info_reset(0); - WARN_ON(xen_cpuhp_setup(xen_cpu_up_prepare_pv, xen_cpu_dead_pv));
local_irq_disable(); diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index 8a10c9a9e2b5..417b339e5c8e 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -15,6 +15,7 @@
#include <xen/interface/xen.h>
+#include <linux/init.h> #include <linux/linkage.h>
.macro xen_pv_trap name @@ -54,6 +55,19 @@ xen_pv_trap entry_INT80_compat #endif xen_pv_trap hypervisor_callback
+ __INIT +ENTRY(xen_early_idt_handler_array) + i = 0 + .rept NUM_EXCEPTION_VECTORS + pop %rcx + pop %r11 + jmp early_idt_handler_array + i*EARLY_IDT_HANDLER_SIZE + i = i + 1 + .fill xen_early_idt_handler_array + i*XEN_EARLY_IDT_HANDLER_SIZE - ., 1, 0xcc + .endr +END(xen_early_idt_handler_array) + __FINIT + hypercall_iret = hypercall_page + __HYPERVISOR_iret * 32 /* * Xen64 iret frame: