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Re: [Xen-devel] [PATCH v4 2/5] x86/msr: Carry on after a non-"safe" MSR access fails without !panic_on_oops
- To: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
- From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
- Date: Mon, 14 Mar 2016 11:48:47 -0700
- Cc: KVM list <kvm@xxxxxxxxxxxxxxx>, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, X86 ML <x86@xxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, xen-devel <Xen-devel@xxxxxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Andy Lutomirski <luto@xxxxxxxxxx>, Paolo Bonzini <pbonzini@xxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
- Delivery-date: Mon, 14 Mar 2016 18:49:30 +0000
- List-id: Xen developer discussion <xen-devel.lists.xen.org>
On Mon, Mar 14, 2016 at 11:40 AM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Mon, Mar 14, 2016 at 11:24 AM, Andy Lutomirski <luto@xxxxxxxxxxxxxx> wrote:
>>
>> The code in my queue is, literally:
>>
>> bool ex_handler_rdmsr_unsafe(const struct exception_table_entry *fixup,
>> struct pt_regs *regs, int trapnr)
>> {
>> WARN_ONCE(1, "unchecked MSR access error: RDMSR from 0x%x",
>> (unsigned int)regs->cx);
>>
>> /* Pretend that the read succeeded and returned 0. */
>> regs->ip = ex_fixup_addr(fixup);
>> regs->ax = 0;
>> regs->dx = 0;
>> return true;
>> }
>> EXPORT_SYMBOL(ex_handler_rdmsr_unsafe);
>
> I guess I can live with this, as long as we also extend the
> early-fault handling to work with the special exception handlers.
OK, will do. I need to rewrork the early IDT code a bit so it
generates a real pt_regs layout, but that's arguably a cleanup anyway.
--Andy
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