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Date:   Wed, 23 Aug 2023 05:42:32 +0000
From:   Wei Liu <wei.liu@kernel.org>
To:     Dexuan Cui <decui@microsoft.com>
Cc:     kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
        linux-hyperv@vger.kernel.org, mikelley@microsoft.com,
        tiala@microsoft.com, tglx@linutronix.de, mingo@redhat.com,
        bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com,
        thomas.lendacky@amd.com, linux-kernel@vger.kernel.org,
        x86@kernel.org
Subject: Re: [PATCH] x86/hyperv: Fix undefined reference to
 isolation_type_en_snp without CONFIG_HYPERV
Message-ID: <ZOWcSKlonRpbNloN@liuwe-devbox-debian-v2>
References: <20230823032008.18186-1-decui@microsoft.com>
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On Tue, Aug 22, 2023 at 08:20:08PM -0700, Dexuan Cui wrote:
> When CONFIG_HYPERV is not set, arch/x86/hyperv/ivm.c is not built (see
> arch/x86/Kbuild), so 'isolation_type_en_snp' in the ivm.c is not defined,
> and this failure happens:
> 
> ld: arch/x86/kernel/cpu/mshyperv.o: in function `ms_hyperv_init_platform':
> arch/x86/kernel/cpu/mshyperv.c:417: undefined reference to `isolation_type_en_snp'
> 
> Fix the failure by testing hv_get_isolation_type() and
> ms_hyperv.paravisor_present for a fully enlightened SNP VM: when
> CONFIG_HYPERV is not set, hv_get_isolation_type() is defined as a
> static inline function that always returns HV_ISOLATION_TYPE_NONE
> (see include/asm-generic/mshyperv.h), so the compiler won't generate any
> code for the ms_hyperv.paravisor_present and static_branch_enable().
> 
> Reported-by: Tom Lendacky <thomas.lendacky@amd.com>
> Closes: https://lore.kernel.org/lkml/b4979997-23b9-0c43-574e-e4a3506500ff@amd.com/
> Fixes: d6e2d6524437 ("x86/hyperv: Add sev-snp enlightened guest static key")
> Signed-off-by: Dexuan Cui <decui@microsoft.com>

Applied. Thanks.