This is a note to let you know that I've just added the patch titled

x86/xen: Support early interrupts in xen pv guests

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-xen-support-early-interrupts-in-xen-pv-guests.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Thu Feb 1 13:45:42 CET 2018

From: Juergen Gross jgross@suse.com Date: Fri, 24 Nov 2017 09:42:21 +0100 Subject: x86/xen: Support early interrupts in xen pv guests

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@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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(-)

--- 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. --- 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 * 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;

/* --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -622,7 +622,7 @@ static struct trap_array_entry trap_arra { 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, u } }

+ 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_sta 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_sta */ 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(); --- 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:

Patches currently in stable-queue which might be from jgross@suse.com are

queue-4.14/xen-netfront-remove-warning-when-unloading-module.patch queue-4.14/x86-xen-support-early-interrupts-in-xen-pv-guests.patch