Re: [PATCH] x86/xen: support early interrupts in xen pv guests
On Fri, 24 Nov 2017, Andy Lutomirski wrote: > On Fri, Nov 24, 2017 at 12:52 AM, Juergen Gross wrote: > > Sorry, Andy, forgot to Cc: you... > > > > On 24/11/17 09:42, Juergen Gross wrote: > >> 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. > > Nice! It would be great to get this into 4.15. I pick it up tomorrow morning Thanks, tglx
Re: [PATCH] x86/xen: support early interrupts in xen pv guests
On Fri, Nov 24, 2017 at 12:52 AM, Juergen Gross wrote: > Sorry, Andy, forgot to Cc: you... > > On 24/11/17 09:42, Juergen Gross wrote: >> 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. Nice! It would be great to get this into 4.15. >> >> Suggested-by: Andy Lutomirski >> Signed-off-by: Juergen Gross >> --- >> 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 3321b446b66c..88754bfd425f 100644 >> --- a/arch/x86/mm/extable.c >> +++ b/arch/x86/mm/extable.c >> @@ -1,6 +1,7 @@ >> #include >> #include >> #include >> +#include >> >> #include >> #include >> @@ -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 5b2b3f3f6531..f2414c6c5e7c 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; >> >> @@ -1262,6 +1270,21 @@ 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 >> @@ -1295,18 +1318,6 @@ 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_
Re: [PATCH] x86/xen: support early interrupts in xen pv guests
Sorry, Andy, forgot to Cc: you... On 24/11/17 09:42, Juergen Gross wrote: > 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 > Signed-off-by: Juergen Gross > --- > 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 3321b446b66c..88754bfd425f 100644 > --- a/arch/x86/mm/extable.c > +++ b/arch/x86/mm/extable.c > @@ -1,6 +1,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -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 5b2b3f3f6531..f2414c6c5e7c 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; > > @@ -1262,6 +1270,21 @@ 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 > @@ -1295,18 +1318,6 @@ 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_6