From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
James Morse <james.morse@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Ard Biesheuvel <ardb@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
kvmarm@lists.cs.columbia.edu, linux-efi@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] arm64/mm: Fix __enable_mmu() for new TGRAN range values
Date: Tue, 9 Mar 2021 20:22:38 +0530 [thread overview]
Message-ID: <718f4b0c-20d9-8588-1268-e5b26690899d@arm.com> (raw)
In-Reply-To: <20210309140527.GB28395@willie-the-truck>
On 3/9/21 7:35 PM, Will Deacon wrote:
> On Mon, Mar 08, 2021 at 02:42:00PM +0000, Marc Zyngier wrote:
>> On Fri, 05 Mar 2021 14:36:09 +0000,
>> Anshuman Khandual <anshuman.khandual@arm.com> wrote:
>>> - switch (cpuid_feature_extract_unsigned_field(mmfr0, tgran_2)) {
>>> - default:
>>> - case 1:
>>> + tgran_2 = cpuid_feature_extract_unsigned_field(mmfr0, tgran_2_shift);
>>> + if (tgran_2 == ID_AA64MMFR0_TGRAN_2_SUPPORTED_NONE) {
>>> kvm_err("PAGE_SIZE not supported at Stage-2, giving up\n");
>>> return -EINVAL;
>>> - case 0:
>>> + } else if (tgran_2 == ID_AA64MMFR0_TGRAN_2_SUPPORTED_DEFAULT) {
>>> kvm_debug("PAGE_SIZE supported at Stage-2 (default)\n");
>>> - break;
>>> - case 2:
>>> + } else if (tgran_2 >= ID_AA64MMFR0_TGRAN_2_SUPPORTED_MIN &&
>>> + tgran_2 <= ID_AA64MMFR0_TGRAN_2_SUPPORTED_MAX) {
>>> kvm_debug("PAGE_SIZE supported at Stage-2 (advertised)\n");
>>> - break;
>>> + } else {
>>> + kvm_err("Unsupported value, giving up\n");
>>> + return -EINVAL;
>>
>> nit: this doesn't say *what* value is unsupported, and I really
>> preferred the switch-case version, such as this:
>>
>> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
>> index 1f22b36a0eff..d267e4b1aec6 100644
>> --- a/arch/arm64/kvm/reset.c
>> +++ b/arch/arm64/kvm/reset.c
>> @@ -312,15 +312,18 @@ int kvm_set_ipa_limit(void)
>>
>> switch (cpuid_feature_extract_unsigned_field(mmfr0, tgran_2)) {
>> default:
>> - case 1:
>> + case ID_AA64MMFR0_TGRAN_2_SUPPORTED_NONE:
>> kvm_err("PAGE_SIZE not supported at Stage-2, giving up\n");
>> return -EINVAL;
>> - case 0:
>> + case ID_AA64MMFR0_TGRAN_2_SUPPORTED_DEFAULT:
>> kvm_debug("PAGE_SIZE supported at Stage-2 (default)\n");
>> break;
>> - case 2:
>> + case ID_AA64MMFR0_TGRAN_2_SUPPORTED_MIN ... ID_AA64MMFR0_TGRAN_2_SUPPORTED_MAX:
>> kvm_debug("PAGE_SIZE supported at Stage-2 (advertised)\n");
>> break;
>> + default:
>> + kvm_err("Unsupported value for TGRAN_2, giving up\n");
>> + return -EINVAL;
>> }
>>
>> kvm_ipa_limit = id_aa64mmfr0_parange_to_phys_shift(parange);
>>
>>
>> Otherwise:
>>
>> Acked-by: Marc Zyngier <maz@kernel.org>
>
> Anshuman -- please can you spin a v2 with the switch syntax as suggested
> above by Marc?
Sure, will do.
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prev parent reply other threads:[~2021-03-09 14:54 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-05 14:36 [PATCH] arm64/mm: Fix __enable_mmu() for new TGRAN range values Anshuman Khandual
2021-03-05 14:51 ` Mark Rutland
2021-03-07 11:54 ` Anshuman Khandual
2021-03-08 13:30 ` Will Deacon
2021-03-08 15:03 ` Mark Rutland
2021-03-08 14:42 ` Marc Zyngier
2021-03-09 14:05 ` Will Deacon
2021-03-09 14:52 ` Anshuman Khandual [this message]
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