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h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=Dp4k76aSEZqb6H3+dvFgTwwZRo4thgbYprD3kCbGuLWdX84AVVpbmoIW9R9cc/MJC c2h2/nX/mor1D1qXiM3EHVMVfGzckNut8HcRMHBaoEseJ9v8JXPURG4QlrYM5RB7mO CHOCamiMpBDkgF62+jVdA8A0oVR4RMcZD64bdz8k= Message-ID: <57426824-5302-4200-8560-8eb67be6b378@linux.microsoft.com> Date: Thu, 27 Feb 2025 16:49:48 -0800 Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Cc: eahariha@linux.microsoft.com, linux-hyperv@vger.kernel.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-acpi@vger.kernel.org, kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org, mhklinux@outlook.com, decui@microsoft.com, catalin.marinas@arm.com, will@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, daniel.lezcano@linaro.org, joro@8bytes.org, robin.murphy@arm.com, arnd@arndb.de, jinankjain@linux.microsoft.com, muminulrussell@gmail.com, skinsburskii@linux.microsoft.com, mrathor@linux.microsoft.com, ssengar@linux.microsoft.com, apais@linux.microsoft.com, Tianyu.Lan@microsoft.com, stanislav.kinsburskiy@gmail.com, gregkh@linuxfoundation.org, vkuznets@redhat.com, prapal@linux.microsoft.com, muislam@microsoft.com, anrayabh@linux.microsoft.com, rafael@kernel.org, lenb@kernel.org, corbet@lwn.net Subject: Re: [PATCH v5 04/10] hyperv: Introduce hv_recommend_using_aeoi() To: Nuno Das Neves References: <1740611284-27506-1-git-send-email-nunodasneves@linux.microsoft.com> <1740611284-27506-5-git-send-email-nunodasneves@linux.microsoft.com> <7749367d-d87d-43f0-8c24-cd08bb4ce1a8@linux.microsoft.com> From: Easwar Hariharan Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/27/2025 4:33 PM, Nuno Das Neves wrote: > On 2/27/2025 3:03 PM, Easwar Hariharan wrote: >> On 2/26/2025 3:07 PM, Nuno Das Neves wrote: >>> Factor out the check for enabling auto eoi, to be reused in root >>> partition code. >>> >>> Signed-off-by: Nuno Das Neves >>> --- >>> drivers/hv/hv.c | 12 +----------- >>> include/asm-generic/mshyperv.h | 13 +++++++++++++ >>> 2 files changed, 14 insertions(+), 11 deletions(-) >>> >> >> >> >>> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h >>> index 258034dfd829..1f46d19a16aa 100644 >>> --- a/include/asm-generic/mshyperv.h >>> +++ b/include/asm-generic/mshyperv.h >>> @@ -77,6 +77,19 @@ extern u64 hv_do_fast_hypercall16(u16 control, u64 input1, u64 input2); >>> bool hv_isolation_type_snp(void); >>> bool hv_isolation_type_tdx(void); >>> >>> +/* >>> + * On architectures where Hyper-V doesn't support AEOI (e.g., ARM64), >>> + * it doesn't provide a recommendation flag and AEOI must be disabled. >>> + */ >>> +static inline bool hv_recommend_using_aeoi(void) >>> +{ >>> +#ifdef HV_DEPRECATING_AEOI_RECOMMENDED >>> + return !(ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED); >>> +#else >>> + return false; >>> +#endif >>> +} >>> + >> >> I must be missing something very basic here, and if so, I apologize, and please enlighten me. >> >> HV_DEPRECATING_AEOI_RECOMMENDED is defined as BIT(9) in include/hyperv/hvgdk_mini.h, and >> asm-generic/mshyperv.h includes that via include/hyperv/hvhdk.h. >> >> If this is the case, when would HV_DEPRECATING_AEOI_RECOMMENDED ever be not defined? >> If it's always defined, do we need the #ifdef? >> > HV_DEPRECATING_AEOI_RECOMMENDED is only defined on x86 (it used to live in x86 hyperv-tlfs.h). > It lives inside a #if defined(CONFIG_X86) block in hvgdk_mini.h. It is a bit confusing since > it is surrounded by other x86-only definitions which are prefixed with HV_X64_. > Ah, thank you. I knew it must be something glaringly obvious in hindsight. With that resolved, Reviewed-by: Easwar Hariharan