From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753572AbdKXPuv (ORCPT ); Fri, 24 Nov 2017 10:50:51 -0500 Received: from mail.kernel.org ([198.145.29.99]:38822 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752288AbdKXPuu (ORCPT ); Fri, 24 Nov 2017 10:50:50 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B5196219AE Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=luto@kernel.org X-Google-Smtp-Source: AGs4zMaYBkJNUWvgOALpiEmLEkpaPodKCQqwrDAizrU/Qy7SIq1HNQVMhKtzg0xKr6ERXlLfqkEjJD39uMm2jukYvuM= MIME-Version: 1.0 In-Reply-To: <055898e5-a122-2f8a-c141-d3bca75a7045@suse.com> References: <20171124084221.30172-1-jgross@suse.com> <055898e5-a122-2f8a-c141-d3bca75a7045@suse.com> From: Andy Lutomirski Date: Fri, 24 Nov 2017 07:50:28 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] x86/xen: support early interrupts in xen pv guests To: Juergen Gross Cc: "linux-kernel@vger.kernel.org" , "xen-devel@lists.xenproject.org" , X86 ML , Boris Ostrovsky , "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , Andrew Lutomirski Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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_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 >> >> +#include >> #include >> >> .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: >> >