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 43643606A31D for ; Thu, 29 Oct 2026 22:54:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=UiyQpipV; dkim=pass (1024-bit key, unprotected) header.d=arm.com header.i=@arm.com header.a=rsa-sha256 header.s=foss header.b=BDH0irSJ 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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Unsubscribe-Post:List-Owner; bh=POwY9K3wYZjvJPalx+6QkgsqJfGo8QCv3p3v7iSCx8U=; b=UiyQpipVEY9y1OQRdDObUvRowG G3BmU9asO1OfoFGTmVnaPCsgUHk7RhexE6nGxpsagxubwpp9UZcxWNYaeNC+68YFObVb1Dz/URiOb 8je2yGGC19EipRHqqR4bIr845kCqovq/e0x0m48WvJvUUrM0iQ+kE9WjZz14J4Vd3sWmgI3naGk8g MWMDYhzSEvoqGuYrg49q2xGdkGnDbLkM5GnrEMo2e1ihxv0O4GMYSiEL7vv2a+9RCMkbNxOrJykFu oI8VRDYZ/egc1lg/6NBi1eUytXT9wnWd2ly7R2THiVmqharmeULKKIXE9/00YkUIw9q0h4Qn3HRM1 iO/uhbYg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMZ0x-0000000AVSe-3P03; Thu, 29 Oct 2026 22:54:32 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xMZ0u-0000000AVRz-1eKl for linux-arm-kernel@lists.infradead.org; Thu, 29 Oct 2026 22:54:30 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 352FB169E; Thu, 29 Oct 2026 15:54:23 -0700 (PDT) Received: from arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0E2043F673; Thu, 29 Oct 2026 15:54:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1793314466; bh=+W+VoreRqIYQsjm9ZjQdyC40IddCPxH6b0QBB2g7Y3c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BDH0irSJKsIvF3lVyzTr15otTHYjyscFtzzcK2NHYxOvYzxveHXWqaGMjHHgVZHsG vINIrvUOSDsQkpU5VyXbVZL4KrLZwF7+8VuyhowwNaKNjHX4P5VdHXfIxAUioo+gm9 Ho9ljIJqirq4qnv/E8nsInssKH/ncXUu8miviacQ= Date: Thu, 29 Oct 2026 22:54:21 +0000 From: Catalin Marinas To: Kameron Carr Cc: haiyangz@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, mhklinux@outlook.com, will@kernel.org, mark.rutland@arm.com, lpieralisi@kernel.org, sudeep.holla@kernel.org, arnd@arndb.de, thuth@redhat.com, linux-hyperv@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, Suzuki K Poulose Subject: Re: [PATCH v5 2/6] firmware: smccc: Detect hypervisor via RSI host call in CCA Realms Message-ID: References: <20261002215725.2015959-1-kameroncarr@linux.microsoft.com> <20261002215725.2015959-3-kameroncarr@linux.microsoft.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261002215725.2015959-3-kameroncarr@linux.microsoft.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261029_155428_739268_792C734B X-CRM114-Status: GOOD ( 26.38 ) X-Spam-Score: -4.4 (----) 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" X-Spam-Status: No, score=-15.9 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 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 + Suzuki On Fri, Oct 02, 2026 at 02:57:21PM -0700, Kameron Carr wrote: > Modify arm_smccc_hypervisor_has_uuid() to check is_realm_world() and > use rsi_host_call() to query the hypervisor vendor UUID when inside a > Realm. The realm path is factored into a helper, > arm_smccc_realm_get_hypervisor_uuid(), that owns a file-static > rsi_host_call buffer (uuid_hc) serialized by a spinlock. > > The RSI-specific includes, file-static state and helper are guarded with > CONFIG_ARM64 because does not build on 32-bit > ARM. > > For non-Realm environments, the existing arm_smccc_1_1_invoke() path > is unchanged. > > Reviewed-by: Michael Kelley > Signed-off-by: Kameron Carr > --- > drivers/firmware/smccc/smccc.c | 41 +++++++++++++++++++++++++++++++++- > 1 file changed, 40 insertions(+), 1 deletion(-) > > diff --git a/drivers/firmware/smccc/smccc.c b/drivers/firmware/smccc/smccc.c > index afc2e4d..7e77170 100644 > --- a/drivers/firmware/smccc/smccc.c > +++ b/drivers/firmware/smccc/smccc.c > @@ -14,6 +14,12 @@ > > #include > > +#ifdef CONFIG_ARM64 > +#include > +#include > +#include > +#endif > + > static u32 smccc_version = ARM_SMCCC_VERSION_1_0; > static enum arm_smccc_conduit smccc_conduit = SMCCC_CONDUIT_NONE; > > @@ -69,12 +75,45 @@ s32 arm_smccc_get_soc_id_revision(void) > } > EXPORT_SYMBOL_GPL(arm_smccc_get_soc_id_revision); > > +#ifdef CONFIG_ARM64 > +static struct rsi_host_call uuid_hc; > +static DEFINE_SPINLOCK(uuid_hc_lock); > + > +/* > + * Helper function to get the hypervisor UUID via an RsiHostCall. > + */ > +static void arm_smccc_realm_get_hypervisor_uuid(struct arm_smccc_res *res) > +{ > + guard(spinlock_irqsave)(&uuid_hc_lock); > + > + memset(&uuid_hc, 0, sizeof(uuid_hc)); > + uuid_hc.gprs[0] = ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID; > + > + if (rsi_host_call(__pa_symbol(&uuid_hc)) != RSI_SUCCESS) { > + res->a0 = SMCCC_RET_NOT_SUPPORTED; > + return; > + } > + > + res->a0 = uuid_hc.gprs[0]; > + res->a1 = uuid_hc.gprs[1]; > + res->a2 = uuid_hc.gprs[2]; > + res->a3 = uuid_hc.gprs[3]; > +} > +#endif > + > bool arm_smccc_hypervisor_has_uuid(const uuid_t *hyp_uuid) > { > struct arm_smccc_res res = {}; > uuid_t uuid; > > - arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, &res); > +#ifdef CONFIG_ARM64 > + if (is_realm_world()) > + arm_smccc_realm_get_hypervisor_uuid(&res); > + else > +#endif > + arm_smccc_1_1_invoke(ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID, > + &res); Is this meant to be generic? I'm not sure the trick to pass ARM_SMCCC_VENDOR_HYP_CALL_UID_FUNC_ID in gprs[0] and forward it to the host is a documented ABI. I think it even confuses other realm guests that don't expect this (e.g. kvm_init_hyp_services()). I thought realms should stick to the RSI interface and not try to guess the host hypervisor. But if you do need this, a better fit would be in hyperv_detect_via_smccc() (if realms don't boot with ACPI). I'll leave it to Sudeep or Suzuki to comment further. -- Catalin