linux-kernel - Re: [PATCH v5 11/19] KVM:VMX: Emulate read and write to CET MSRs

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Date:   Fri, 4 Aug 2023 16:28:52 +0800
From:   Chao Gao <chao.gao@...el.com>
To:     Yang Weijiang <weijiang.yang@...el.com>
CC:     <seanjc@...gle.com>, <pbonzini@...hat.com>, <peterz@...radead.org>,
        <john.allen@....com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <rick.p.edgecombe@...el.com>,
        <binbin.wu@...ux.intel.com>
Subject: Re: [PATCH v5 11/19] KVM:VMX: Emulate read and write to CET MSRs

>+	case MSR_IA32_PL0_SSP ... MSR_IA32_INT_SSP_TAB:
>+		if (!kvm_cet_is_msr_accessible(vcpu, msr_info))
>+			return 1;
>+		if (is_noncanonical_address(data, vcpu))
>+			return 1;
>+		if (!IS_ALIGNED(data, 4))
>+			return 1;

Why should MSR_IA32_INT_SSP_TAB be 4-byte aligned? I don't see
this requirement in SDM.

IA32_INTERRUPT_SSP_TABLE_ADDR:

Linear address of a table of seven shadow
stack pointers that are selected in IA-32e
mode using the IST index (when not 0) from
the interrupt gate descriptor. (R/W)
This MSR is not present on processors that
do not support Intel 64 architecture. This
field cannot represent a non-canonical
address.