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Date:   Sat, 15 Apr 2023 00:32:46 +0800
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Subject: Re: [RFC PATCH V4 13/17] x86/sev: Add Check of #HV event in path
To:     Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc:     luto@kernel.org, tglx@linutronix.de, mingo@redhat.com,
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References: <20230403174406.4180472-1-ltykernel@gmail.com>
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From:   Tianyu Lan <ltykernel@gmail.com>
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On 4/14/2023 7:02 PM, Pankaj Gupta wrote:
>> +void check_hv_pending_irq_enable(void)
>> +{
>> +       struct pt_regs regs;
>> +
>> +       if (!cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
>> +               return;
>> +
>> +       memset(&regs, 0, sizeof(struct pt_regs));
>> +       asm volatile("movl %%cs, %%eax;" : "=a" (regs.cs));
>> +       asm volatile("movl %%ss, %%eax;" : "=a" (regs.ss));
>> +       regs.orig_ax = 0xffffffff;
>> +       regs.flags = native_save_fl();
>> +
>> +       /*
>> +        * Disable irq when handle pending #HV events after
>> +        * re-enabling irq.
>> +        */
>> +       asm volatile("cli" : : : "memory");
> Just curious, Does the hypervisor injects irqs via doorbell page when
> interrupts are disabled with "cli" ? Trying to understand the need to
> cli/sti covering on "do_exc_hv".


Hi Pankaj:
	Thanks for your review. Yes, Hypervisor still injects #HV exception 
when irq was disabled check_hv_pending() is called when
there is a #HV exception. It checks irq flag and return back without 
handling irq event when irq was disabled.