From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C2FA7606A33A for ; Thu, 12 Nov 2026 17:50:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=c5mMOPSV; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.a=rsa-sha256 header.s=default header.b=paozY693 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; 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a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1794505805; bh=FOHX458T5nlJ4b9+AlmECqof587GCWew+NK4zoiJyAE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=paozY693cvLDuf4U/crDEhukiZGU+ENNK3akzY0Z75lnrf/hk6O4Biq9Pjs6VA36O VvLZLX2Q5xAFWYNNkEEf80GOPTs8m23Qnbp1U10U+ZMk0anGkAotQVek9ACBl8Qr7/ 4ViVDBAcFE+Bz8si1aupeZORaBNIHjnWF9wigGQo= Message-ID: Date: Thu, 12 Nov 2026 09:49:54 -0800 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v6 4/6] Drivers: hv: Mark shared memory as decrypted for CCA Realms To: Mukesh R Cc: Michael Kelley , "decui@microsoft.com" , "haiyangz@microsoft.com" , "wei.liu@kernel.org" , "arnd@arndb.de" , "catalin.marinas@arm.com" , "linux-arch@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "lpieralisi@kernel.org" , "mark.rutland@arm.com" , "sudeep.holla@kernel.org" , "thuth@redhat.com" , "will@kernel.org" References: <20261031001412.4150488-1-kameroncarr@linux.microsoft.com> <20261031001412.4150488-5-kameroncarr@linux.microsoft.com> Content-Language: en-US From: Kameron Carr In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-17.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261112_095011_055587_EEE01D5B X-CRM114-Status: GOOD ( 19.04 ) X-Spam-Score: -2.8 (--) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" On 11/11/2026 6:43 PM, Mukesh R wrote: > On 11/11/26 10:01, Michael Kelley wrote: >> From: Kameron Carr Sent: Friday, October 30, 2026 5:14 PM >>> >>> In hv_common_cpu_init(), the per-CPU hypercall input/output pages need >>> to be marked as decrypted (shared) for confidential VM isolation types. >>> This is already done for SNP and TDX isolation; extend the same handling >>> to Arm CCA Realm guests so that the host hypervisor can access the >>> shared hypercall buffers. >>> >>> is_realm_world() is declared in include/linux/arm-rsi-cmds.h which only >>> builds on arm64 (it includes ), so using it directly in >>> the arch-neutral drivers/hv/hv_common.c would break the x86 build. >>> Introduce a Hyper-V-specific helper following the established >>> hv_isolation_type_snp() / hv_isolation_type_tdx() pattern. >>> >>> On architectures other than arm64 the weak default keeps the existing >>> behaviour. >>> >>> Reviewed-by: Michael Kelley >>> Signed-off-by: Kameron Carr >>> --- >>>   arch/arm64/hyperv/mshyperv.c   |  5 +++++ >>>   drivers/hv/hv_common.c         | 17 +++++++++++++---- >>>   include/asm-generic/mshyperv.h |  1 + >>>   3 files changed, 19 insertions(+), 4 deletions(-) >>> >>> diff --git a/arch/arm64/hyperv/mshyperv.c b/arch/arm64/hyperv/mshyperv.c >>> index 46ab2da..da6c3aa0 100644 >>> --- a/arch/arm64/hyperv/mshyperv.c >>> +++ b/arch/arm64/hyperv/mshyperv.c >>> @@ -182,3 +182,8 @@ bool hv_is_hyperv_initialized(void) >>>       return hyperv_initialized; >>>   } >>>   EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized); >>> + >>> +bool hv_isolation_type_cca(void) >>> +{ >>> +    return is_realm_world(); >>> +} >>> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c >>> index 31256cb..a60c92c 100644 >>> --- a/drivers/hv/hv_common.c >>> +++ b/drivers/hv/hv_common.c >>> @@ -476,6 +476,7 @@ int hv_common_cpu_init(unsigned int cpu) >>>       u64 msr_vp_index; >>>       gfp_t flags; >>>       const int pgcount = hv_output_page_exists() ? 2 : 1; >>> +    const size_t alloc_size = ALIGN((size_t)pgcount * HV_HYP_PAGE_SIZE, PAGE_SIZE); >>>       void *mem; >>>       int ret = 0; >>> >>> @@ -489,7 +490,7 @@ int hv_common_cpu_init(unsigned int cpu) >>>        * online and then taken offline >>>        */ >>>       if (!*inputarg) { >>> -        mem = kmalloc_array(pgcount, HV_HYP_PAGE_SIZE, flags); >>> +        mem = kmalloc(alloc_size, flags); >>>           if (!mem) >>>               return -ENOMEM; >>> >>> @@ -499,14 +500,16 @@ int hv_common_cpu_init(unsigned int cpu) >>>           } >>> >>>           if (!ms_hyperv.paravisor_present && >>> -            (hv_isolation_type_snp() || hv_isolation_type_tdx())) { >>> -            ret = set_memory_decrypted((unsigned long)mem, pgcount); >>> +            (hv_isolation_type_snp() || hv_isolation_type_tdx() || >>> +             hv_isolation_type_cca())) { >> >> Could this big "if" statement use "hv_is_isolation_supported()" instead >> of explicitly testing for each CoCo VM type? I ask partly because >> Mukesh Rathor has just submitted a patch [1] that introduces a new >> function that does something almost exactly the same as >> hv_is_isolation_supported() and uses it here. > >>> +            (hv_isolation_type_snp() || hv_isolation_type_tdx() || >>> +             hv_isolation_type_cca())) { > > With my change, this will become: > >         (hv_isolation_hw_cvm() || hv_isolation_type_cca())) { Any reason you wouldn't change hv_isolation_hw_cvm() to return hv_isolation_type_snp() || hv_isolation_type_tdx() || hv_isolation_type_cca() That would seem more logical to me. -- Regards, Kameron > > Thanks, > -Mukesh > > >> You don't provide the non-stub hv_is_isolation_supported() until >> Patch 6 of this series, but the weak stub should allow everything to >> build if a bisection splits this patch series. >> >> Michael >> >> [1] https://lore.kernel.org/linux-hyperv/20261111022036.351231-2-mrathor@linux.microsoft.com/ >> >>> +            ret = set_memory_decrypted((unsigned long)mem, >>> +                           alloc_size >> PAGE_SHIFT); >>>               if (ret) { >>>                   /* It may be unsafe to free 'mem' */ >>>                   return ret; >>>               } >>> >>> -            memset(mem, 0x00, pgcount * HV_HYP_PAGE_SIZE); >>> +            memset(mem, 0x00, alloc_size); >>>           } >>> >>>           /* >>> @@ -666,6 +669,12 @@ bool __weak hv_isolation_type_tdx(void) >>>   } >>>   EXPORT_SYMBOL_GPL(hv_isolation_type_tdx); >>> >>> +bool __weak hv_isolation_type_cca(void) >>> +{ >>> +    return false; >>> +} >>> +EXPORT_SYMBOL_GPL(hv_isolation_type_cca); >>> + >>>   void __weak hv_setup_vmbus_handler(void (*handler)(void)) >>>   { >>>   } >>> diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h >>> index bf601d6..1fa79ab 100644 >>> --- a/include/asm-generic/mshyperv.h >>> +++ b/include/asm-generic/mshyperv.h >>> @@ -79,6 +79,7 @@ u64 hv_do_fast_hypercall16(u16 control, u64 input1, u64 >>> input2); >>> >>>   bool hv_isolation_type_snp(void); >>>   bool hv_isolation_type_tdx(void); >>> +bool hv_isolation_type_cca(void); >>> >>>   /* >>>    * On architectures where Hyper-V doesn't support AEOI (e.g., ARM64), >>> -- >>> 2.45.4 >>>