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From: Paolo Bonzini <pbonzini@redhat.com>
To: Yang Zhong <yang.zhong@intel.com>, kvm@vger.kernel.org
Cc: seanjc@google.com, jun.nakajima@intel.com, kevin.tian@intel.com,
	jing2.liu@linux.intel.com
Subject: Re: [PATCH v2 3/3] selftest: kvm: Support amx selftest
Date: Wed, 22 Dec 2021 16:15:02 +0100	[thread overview]
Message-ID: <2348d4e6-fb14-9c5b-5a6a-829d4ecd1839@redhat.com> (raw)
In-Reply-To: <20211222214731.2912361-4-yang.zhong@intel.com>

On 12/22/21 22:47, Yang Zhong wrote:
> +	/* Trigger #NM exception */
> +	__tileloadd(tiledata);
> +	GUEST_SYNC(10);
> +
> +	GUEST_DONE();
> +}
> +
> +void guest_nm_handler(struct ex_regs *regs)
> +{
> +	/* Check if #NM is triggered by XFEATURE_MASK_XTILEDATA */
> +	GUEST_SYNC(7);
> +	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILEDATA);
> +	GUEST_SYNC(8);
> +	GUEST_ASSERT(rdmsr(MSR_IA32_XFD_ERR) == XFEATURE_MASK_XTILEDATA);
> +	/* Clear xfd_err */
> +	wrmsr(MSR_IA32_XFD_ERR, 0);
> +	regs->rip += 3;
> +	GUEST_SYNC(9);
> +}

I don't understand why "regs->rip += 3" is needed though.

My idea was that, after GUEST_SYNC(9) and IRET, the guest would execute 
__tileloadd again; this time without generating #NM, so that after 
GUEST_SYNC(10) the host sees the loaded data in TMM0.

Thanks,

Paolo

  reply	other threads:[~2021-12-22 15:15 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-22 21:47 [PATCH v2 0/3] AMX KVM selftest Yang Zhong
2021-12-22 14:05 ` Paolo Bonzini
2021-12-22 21:47 ` [WARNING: UNSCANNABLE EXTRACTION FAILED][PATCH v2 1/3] selftest: kvm: Reorder vcpu_load_state steps for AMX Yang Zhong
2022-01-12 21:05   ` Sean Christopherson
2022-01-13  6:31     ` Yang Zhong
2021-12-22 21:47 ` [PATCH v2 2/3] selftest: kvm: Move struct kvm_x86_state to header Yang Zhong
2021-12-22 21:47 ` [PATCH v2 3/3] selftest: kvm: Support amx selftest Yang Zhong
2021-12-22 15:15   ` Paolo Bonzini [this message]
2021-12-23  2:38     ` Yang Zhong

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