From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 09984234960; Tue, 10 Dec 2024 16:40:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733848851; cv=none; b=pweoQsT80nT9wadjYq1TqKAi/Jg/MTlvv2FHpb6qJ/uIb3fpuj23yPrnI5kBtIjfr9tD563Y+WbdIQP6Zuhj1whzoQB5XeVDBzTMdnG+XForB6SoHI4cPpHTdoD4ZR6GDX8nfDr/Q5VQZTqhllPM59ejKIGPBJ5iExeQ9jafyY4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733848851; c=relaxed/simple; bh=bNrc3/QIRuMRADX4i6xidePb7Se8rnZoHFgWuntFk6o=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=oFCpfv8qG8c8jO7gPWUGOy46hsi4Cvj5OLubgtaa4VigQlAnJG2D/0JX00wI6U6zUG600ZXsKVOagBRzOoc08pZJlhMpbNTEtnELf2g/AzNlZM50ryBOpyY1WMFPgZsoQwL3JD0ngSDGwJZ4pQV8ZGPOO2pO8OXU7uc6B34DNhM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=qaAvYq7l; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="qaAvYq7l" Received: from [10.16.84.29] (unknown [131.107.8.93]) by linux.microsoft.com (Postfix) with ESMTPSA id 564502047222; Tue, 10 Dec 2024 08:40:49 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 564502047222 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1733848849; bh=jrmNUEzHaPbfzPastsRVKoN7SSf1AJHpgCYDuVUBkcs=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=qaAvYq7lyqspuQZ7OkIAAqOTvmA+2X29R4IObrDpeT1/2dvBSeRobjCAh6lzuXTIB mCRwtak/ZzDJ5+IqnZv+ZWmlbSk5oi8gPenZI/luDYlvBia7HUu+Z7kvfxa3KjhD8E TnsRBHVn/f7nO8STVaJc0gW220fXwfN8VhaB3pdg= Message-ID: Date: Tue, 10 Dec 2024 08:40:49 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/2] hyperv: Move hv_current_partition_id to arch-generic code To: Michael Kelley , "linux-hyperv@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , "linux-arch@vger.kernel.org" Cc: "kys@microsoft.com" , "haiyangz@microsoft.com" , "wei.liu@kernel.org" , "decui@microsoft.com" , "catalin.marinas@arm.com" , "will@kernel.org" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "arnd@arndb.de" , "jinankjain@linux.microsoft.com" , "muminulrussell@gmail.com" , "skinsburskii@linux.microsoft.com" , "mukeshrathor@microsoft.com" References: <1733523707-15954-1-git-send-email-nunodasneves@linux.microsoft.com> <1733523707-15954-2-git-send-email-nunodasneves@linux.microsoft.com> Content-Language: en-US From: Nuno Das Neves In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/7/2024 7:01 PM, Michael Kelley wrote: > From: Nuno Das Neves Sent: Friday, December 6, 2024 2:22 PM >> >> Make hv_current_partition_id available in both x86_64 and arm64. >> This feature isn't specific to x86_64 and will be needed by common >> code. >> >> While at it, replace the BUG()s with WARN()s. Failing to get the id >> need not crash the machine (although it is a very bad sign). >> >> Signed-off-by: Nuno Das Neves >> --- >> arch/arm64/hyperv/mshyperv.c | 3 +++ >> arch/x86/hyperv/hv_init.c | 25 +------------------------ >> arch/x86/include/asm/mshyperv.h | 2 -- >> drivers/hv/hv_common.c | 23 +++++++++++++++++++++++ >> include/asm-generic/mshyperv.h | 2 ++ >> 5 files changed, 29 insertions(+), 26 deletions(-) >> >> diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c >> index b1a4de4eee29..5050e748d266 100644 >> --- a/arch/arm64/hyperv/mshyperv.c >> +++ b/arch/arm64/hyperv/mshyperv.c >> @@ -19,6 +19,9 @@ >> >> static bool hyperv_initialized; >> >> +u64 hv_current_partition_id = HV_PARTITION_ID_SELF; >> +EXPORT_SYMBOL_GPL(hv_current_partition_id); >> + > > Instead of adding a definition of hv_current_partition_id on > the arm64 side, couldn't the definition on the x86 side in > hv_init.c be moved to hv_common.c (or maybe somewhere > else that is specific to running in the root partition, per my > comments in the cover letter), so there is only one definition > shared by both architectures? > Yes, that's a better idea. >> int hv_get_hypervisor_version(union hv_hypervisor_version_info *info) >> { >> hv_get_vpreg_128(HV_REGISTER_HYPERVISOR_VERSION, >> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c >> index 95eada2994e1..950f5ccdb9d9 100644 >> --- a/arch/x86/hyperv/hv_init.c >> +++ b/arch/x86/hyperv/hv_init.c >> @@ -35,7 +35,7 @@ >> #include >> #include >> >> -u64 hv_current_partition_id = ~0ull; >> +u64 hv_current_partition_id = HV_PARTITION_ID_SELF; >> EXPORT_SYMBOL_GPL(hv_current_partition_id); >> >> void *hv_hypercall_pg; >> @@ -394,24 +394,6 @@ static void __init hv_stimer_setup_percpu_clockev(void) >> old_setup_percpu_clockev(); >> } >> >> -static void __init hv_get_partition_id(void) >> -{ >> - struct hv_get_partition_id *output_page; >> - u64 status; >> - unsigned long flags; >> - >> - local_irq_save(flags); >> - output_page = *this_cpu_ptr(hyperv_pcpu_output_arg); >> - status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page); >> - if (!hv_result_success(status)) { >> - /* No point in proceeding if this failed */ >> - pr_err("Failed to get partition ID: %lld\n", status); >> - BUG(); >> - } >> - hv_current_partition_id = output_page->partition_id; >> - local_irq_restore(flags); >> -} >> - >> #if IS_ENABLED(CONFIG_HYPERV_VTL_MODE) >> static u8 __init get_vtl(void) >> { >> @@ -606,11 +588,6 @@ void __init hyperv_init(void) >> >> register_syscore_ops(&hv_syscore_ops); >> >> - if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID) >> - hv_get_partition_id(); >> - >> - BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull); >> - >> #ifdef CONFIG_PCI_MSI >> /* >> * If we're running as root, we want to create our own PCI MSI domain. >> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h >> index 5f0bc6a6d025..9eeca2a6d047 100644 >> --- a/arch/x86/include/asm/mshyperv.h >> +++ b/arch/x86/include/asm/mshyperv.h >> @@ -44,8 +44,6 @@ extern bool hyperv_paravisor_present; >> >> extern void *hv_hypercall_pg; >> >> -extern u64 hv_current_partition_id; >> - >> extern union hv_ghcb * __percpu *hv_ghcb_pg; >> >> bool hv_isolation_type_snp(void); >> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c >> index 7a35c82976e0..819bcfd2b149 100644 >> --- a/drivers/hv/hv_common.c >> +++ b/drivers/hv/hv_common.c >> @@ -278,11 +278,34 @@ static void hv_kmsg_dump_register(void) >> } >> } >> >> +static void __init hv_get_partition_id(void) >> +{ >> + struct hv_get_partition_id *output_page; >> + u64 status; >> + unsigned long flags; >> + >> + local_irq_save(flags); >> + output_page = *this_cpu_ptr(hyperv_pcpu_output_arg); >> + status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page); >> + if (!hv_result_success(status)) { >> + local_irq_restore(flags); >> + WARN(true, "Failed to get partition ID: %lld\n", status); >> + return; >> + } >> + hv_current_partition_id = output_page->partition_id; >> + local_irq_restore(flags); >> +} >> + >> int __init hv_common_init(void) >> { >> int i; >> union hv_hypervisor_version_info version; >> >> + if (ms_hyperv.priv_high & HV_ACCESS_PARTITION_ID) >> + hv_get_partition_id(); > > hv_get_partition_id() uses the hyperv_pcpu_output_arg, and at > this point, hyperv_pcpu_output_arg isn't set. That setup > is done later in hv_common_init(). > >> + >> + WARN_ON(hv_root_partition && hv_current_partition_id == HV_PARTITION_ID_SELF); >> + > > Since the hypercall will fail cleanly if the calling VM doesn't > have the HV_ACCESS_PARTITION_ID privilege, could the > above be simplified to just this? > > if (hv_root_partition) > hv_get_partition_id(): > > A non-root partition VM doesn't need to get the partition ID, while a > root partition should have the privilege. If the hypercall fails, there's > already a WARN, so there's no value in doing another WARN. Also if > the hypercall succeeds, it presumably returns a specific partitionID, not > HV_PARTITION_ID_SELF, so we know we have what we want. > > There's already an "if (hv_root_partition)" statement for setting up > the hyperv_pcpu_output_arg. The call to hv_get_partition_id() could > go under that existing "if" *after* the hyperv_pcpu_output_arg is > set. :-) > Thank you, that makes sense. I'll make the changes you suggested for v2. Nuno > Michael > >> /* Get information about the Hyper-V host version */ >> if (!hv_get_hypervisor_version(&version)) >> pr_info("Hyper-V: Host Build %d.%d.%d.%d-%d-%d\n", >> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h >> index 8fe7aaab2599..8c4ff6e9aae7 100644 >> --- a/include/asm-generic/mshyperv.h >> +++ b/include/asm-generic/mshyperv.h >> @@ -60,6 +60,8 @@ struct ms_hyperv_info { >> extern struct ms_hyperv_info ms_hyperv; >> extern bool hv_nested; >> >> +extern u64 hv_current_partition_id; >> + >> extern void * __percpu *hyperv_pcpu_input_arg; >> extern void * __percpu *hyperv_pcpu_output_arg; >> >> -- >> 2.34.1