From: Peter Zijlstra <peterz@infradead.org>
To: Xin Li <xin3.li@intel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
kvm@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com,
seanjc@google.com, pbonzini@redhat.com, kevin.tian@intel.com
Subject: Re: [RESEND PATCH 2/6] x86/traps: add a system interrupt table for system interrupt dispatch
Date: Thu, 10 Nov 2022 09:56:01 +0100 [thread overview]
Message-ID: <Y2y8obdYDXo9vlH/@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20221110061545.1531-3-xin3.li@intel.com>
On Wed, Nov 09, 2022 at 10:15:41PM -0800, Xin Li wrote:
> Upon receiving an external interrupt, KVM VMX reinjects it through
> calling the interrupt handler in its IDT descriptor on the current
> kernel stack, which essentially uses the IDT as an interrupt dispatch
> table.
>
> However the IDT is one of the lowest level critical data structures
> between a x86 CPU and the Linux kernel, we should avoid using it
> *directly* whenever possible, espeically in a software defined manner.
>
> On x86, external interrupts are divided into the following groups
> 1) system interrupts
> 2) external device interrupts
> With the IDT, system interrupts are dispatched through the IDT
> directly, while external device interrupts are all routed to the
> external interrupt dispatch function common_interrupt(), which
> dispatches external device interrupts through a per-CPU external
> interrupt dispatch table vector_irq.
>
> To eliminate dispatching external interrupts through the IDT, add
> a system interrupt handler table for dispatching a system interrupt
> to its corresponding handler directly. Thus a software based dispatch
> function will be:
>
> void external_interrupt(struct pt_regs *regs, u8 vector)
> {
> if (is_system_interrupt(vector))
> system_interrupt_handler_table[vector_to_sysvec(vector)](regs);
> else /* external device interrupt */
> common_interrupt(regs, vector);
> }
>
> What's more, with the Intel FRED (Flexible Return and Event Delivery)
> architecture, IDT, the hardware based event dispatch table, is gone,
> and the Linux kernel needs to dispatch events to their handlers with
> vector to handler mappings, the dispatch function external_interrupt()
> is also needed.
>
> Signed-off-by: H. Peter Anvin (Intel) <hpa@zytor.com>
> Signed-off-by: Xin Li <xin3.li@intel.com>
This is not a valid SOB, it would suggest hpa is the author, but he's
not in in From.
> ---
> arch/x86/include/asm/traps.h | 8 ++++++
> arch/x86/kernel/traps.c | 55 ++++++++++++++++++++++++++++++++++++
> 2 files changed, 63 insertions(+)
>
> diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h
> index 47ecfff2c83d..3dc63d753bda 100644
> --- a/arch/x86/include/asm/traps.h
> +++ b/arch/x86/include/asm/traps.h
> @@ -47,4 +47,12 @@ void __noreturn handle_stack_overflow(struct pt_regs *regs,
> struct stack_info *info);
> #endif
>
> +/*
> + * How system interrupt handlers are called.
> + */
> +#define DECLARE_SYSTEM_INTERRUPT_HANDLER(f) \
> + void f (struct pt_regs *regs __maybe_unused, \
> + unsigned long vector __maybe_unused)
> +typedef DECLARE_SYSTEM_INTERRUPT_HANDLER((*system_interrupt_handler));
> +
> #endif /* _ASM_X86_TRAPS_H */
> diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
> index 178015a820f0..95dd917ef9ad 100644
> --- a/arch/x86/kernel/traps.c
> +++ b/arch/x86/kernel/traps.c
> @@ -1444,6 +1444,61 @@ DEFINE_IDTENTRY_SW(iret_error)
> }
> #endif
>
> +#define SYSV(x,y) [(x) - FIRST_SYSTEM_VECTOR] = (system_interrupt_handler)y
> +
> +#pragma GCC diagnostic push
> +#pragma GCC diagnostic ignored "-Wcast-function-type"
How does this not break CFI ?
next prev parent reply other threads:[~2022-11-10 8:57 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-10 6:15 [RESEND PATCH 0/6] x86/traps,VMX: implement software based NMI/IRQ dispatch for VMX NMI/IRQ reinjection Xin Li
2022-11-10 6:15 ` [RESEND PATCH 1/6] x86/traps: let common_interrupt() handle IRQ_MOVE_CLEANUP_VECTOR Xin Li
2022-11-10 18:59 ` Ashok Raj
2022-11-10 22:09 ` Li, Xin3
2022-11-10 6:15 ` [RESEND PATCH 2/6] x86/traps: add a system interrupt table for system interrupt dispatch Xin Li
2022-11-10 8:56 ` Peter Zijlstra [this message]
2022-11-10 19:55 ` Li, Xin3
2022-11-10 20:36 ` Li, Xin3
2022-11-10 21:12 ` Nathan Chancellor
2022-11-10 23:00 ` Li, Xin3
2022-11-11 0:08 ` Nathan Chancellor
2022-11-11 3:03 ` Li, Xin3
2022-11-11 8:58 ` Peter Zijlstra
2022-11-11 1:12 ` Tian, Kevin
2022-11-11 3:54 ` Li, Xin3
2022-11-11 8:55 ` Peter Zijlstra
2022-11-11 22:07 ` H. Peter Anvin
2022-11-12 9:47 ` Peter Zijlstra
2022-11-10 6:15 ` [RESEND PATCH 3/6] x86/traps: add install_system_interrupt_handler() Xin Li
2022-11-10 6:15 ` [RESEND PATCH 4/6] x86/traps: add external_interrupt() to dispatch external interrupts Xin Li
2022-11-10 16:24 ` Sean Christopherson
2022-11-10 18:02 ` Li, Xin3
2022-11-10 20:10 ` Sean Christopherson
2022-11-10 6:15 ` [RESEND PATCH 5/6] KVM: x86/VMX: add kvm_vmx_reinject_nmi_irq() for NMI/IRQ reinjection Xin Li
2022-11-10 9:03 ` Peter Zijlstra
2022-11-10 20:53 ` Li, Xin3
2022-11-11 9:15 ` Peter Zijlstra
2022-11-11 12:04 ` Paolo Bonzini
2022-11-11 12:19 ` Peter Zijlstra
2022-11-11 12:48 ` Paolo Bonzini
2022-11-11 14:23 ` Peter Zijlstra
2022-11-11 16:35 ` Andrew Cooper
2022-11-11 22:22 ` H. Peter Anvin
2022-11-12 0:08 ` Andrew Cooper
2022-11-11 18:06 ` Li, Xin3
2022-11-11 19:33 ` Peter Zijlstra
2022-11-12 6:35 ` Li, Xin3
2022-11-14 4:39 ` Li, Xin3
2022-11-14 9:08 ` Peter Zijlstra
2022-11-15 7:50 ` Li, Xin3
2022-11-15 9:17 ` Peter Zijlstra
2022-11-17 3:37 ` Li, Xin3
2022-11-17 15:51 ` Sean Christopherson
2022-11-18 0:05 ` Li, Xin3
2022-11-22 13:00 ` Li, Xin3
2022-11-22 20:52 ` Sean Christopherson
2022-11-23 8:31 ` Li, Xin3
2022-11-23 20:42 ` Sean Christopherson
2022-11-24 3:40 ` Li, Xin3
2022-11-28 16:26 ` Sean Christopherson
2022-11-24 9:46 ` Peter Zijlstra
2022-11-28 19:05 ` Sean Christopherson
2022-11-23 9:16 ` Peter Zijlstra
2022-11-23 19:18 ` Sean Christopherson
2022-11-11 22:15 ` H. Peter Anvin
2022-11-10 6:15 ` [RESEND PATCH 6/6] x86/traps: remove unused NMI entry exc_nmi_noist() Xin Li
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