From nobody Wed Dec 17 10:44:35 2025 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9AC732D062F; Wed, 8 Oct 2025 23:34:26 +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=1759966469; cv=none; b=SClw3rv65rbE3a9xThLgEXJTSiMRfudob7ARh7Im3O5t2B6flaPXQAW4+ZkLNlOAtGM3gN6E1jKjLITjZl9lfXZP3HwIdMdHAmQgoxSDc8HhHkvJM1m4SnhGG4anlyuqPYy4QQaNdrK/xQd7No0BjZ3kUfryrm/3lIZ+331DBeQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1759966469; c=relaxed/simple; bh=eG7zc//LpFoEO3eRrr92k38X0fvy9hYXLg93S/pYppQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=XJtVveqNIqKeSILrkCu516xjdPiEHVMMp6kBHIQHz6kT+JDkt9ssIVvyyPV2TvYfau+kGsnO0jR8HN8zmbmGOmgzb9U2CFg6fa4u2YgmGKhf1LrN1fRNZZcRCi9h1GqXSq3bmrlfjTLqE/bZgKZrevC9D3wDgt+QKw3ZOgCNtN4= 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=FveomI1Q; 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="FveomI1Q" Received: from romank-3650.corp.microsoft.com (unknown [131.107.1.188]) by linux.microsoft.com (Postfix) with ESMTPSA id B4B282116267; Wed, 8 Oct 2025 16:34:25 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com B4B282116267 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1759966465; bh=21TxUcvrQ87lu8KrWeAmRDEi5bS6RSoLFSqMIZfttVE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FveomI1QC1gJDGGAVhhPITSfvGvtrki+lZariJ7UJWKGEwomrZpob4g5irpKlxxtZ P9+MqYOhBaYcUMzAHY1AA/OLNYAkIQmP5WorE9Ogfg+U+n4nZJKpx06H/PZg2S2Tgi 4YfvA94jiHj9FRm1FnsTGCUimSmYAKa/jlC5TMLo= From: Roman Kisel To: arnd@arndb.de, bp@alien8.de, bagasdotme@gmail.com, corbet@lwn.net, dave.hansen@linux.intel.com, decui@microsoft.com, haiyangz@microsoft.com, hpa@zytor.com, kys@microsoft.com, mikelley@microsoft.com, mingo@redhat.com, tglx@linutronix.de, Tianyu.Lan@microsoft.com, wei.liu@kernel.org, x86@kernel.org, linux-hyperv@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org Cc: benhill@microsoft.com, bperkins@microsoft.com, sunilmut@microsoft.com Subject: [PATCH hyperv-next v7 05/17] arch/x86: mshyperv: Trap on access for some synthetic MSRs Date: Wed, 8 Oct 2025 16:34:07 -0700 Message-ID: <20251008233419.20372-6-romank@linux.microsoft.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251008233419.20372-1-romank@linux.microsoft.com> References: <20251008233419.20372-1-romank@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" hv_set_non_nested_msr() has special handling for SINT MSRs when a paravisor is present. In addition to updating the MSR on the host, the mirror MSR in the paravisor is updated, including with the proxy bit. But with Confidential VMBus, the proxy bit must not be used, so add a special case to skip it. Signed-off-by: Roman Kisel Reviewed-by: Alok Tiwari Reviewed-by: Tianyu Lan Reviewed-by: Michael Kelley --- arch/x86/kernel/cpu/mshyperv.c | 29 +++++++++++++++++++++++++---- drivers/hv/hv_common.c | 5 +++++ include/asm-generic/mshyperv.h | 1 + 3 files changed, 31 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index af5a3bbbca9f..a42e72c415b5 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -28,6 +28,7 @@ #include #include #include +#include #include #include #include @@ -43,6 +44,12 @@ bool hyperv_paravisor_present __ro_after_init; EXPORT_SYMBOL_GPL(hyperv_paravisor_present); =20 #if IS_ENABLED(CONFIG_HYPERV) +/* + * When running with the paravisor, controls proxying the synthetic interr= upts + * from the host + */ +static bool hv_para_sint_proxy; + static inline unsigned int hv_get_nested_msr(unsigned int reg) { if (hv_is_sint_msr(reg)) @@ -79,17 +86,31 @@ EXPORT_SYMBOL_GPL(hv_get_non_nested_msr); void hv_set_non_nested_msr(unsigned int reg, u64 value) { if (hv_is_synic_msr(reg) && ms_hyperv.paravisor_present) { + /* The hypervisor will get the intercept. */ hv_ivm_msr_write(reg, value); =20 - /* Write proxy bit via wrmsl instruction */ - if (hv_is_sint_msr(reg)) - wrmsrq(reg, value | 1 << 20); + /* Using wrmsrq so the following goes to the paravisor. */ + if (hv_is_sint_msr(reg)) { + union hv_synic_sint sint =3D { .as_uint64 =3D value }; + + sint.proxy =3D hv_para_sint_proxy; + native_wrmsrq(reg, sint.as_uint64); + } } else { - wrmsrq(reg, value); + native_wrmsrq(reg, value); } } EXPORT_SYMBOL_GPL(hv_set_non_nested_msr); =20 +/* + * Enable or disable proxying synthetic interrupts + * to the paravisor. + */ +void hv_para_set_sint_proxy(bool enable) +{ + hv_para_sint_proxy =3D enable; +} + /* * Get the SynIC register value from the paravisor. */ diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c index 8756ca834546..1a5c7a358971 100644 --- a/drivers/hv/hv_common.c +++ b/drivers/hv/hv_common.c @@ -716,6 +716,11 @@ u64 __weak hv_tdx_hypercall(u64 control, u64 param1, u= 64 param2) } EXPORT_SYMBOL_GPL(hv_tdx_hypercall); =20 +void __weak hv_para_set_sint_proxy(bool enable) +{ +} +EXPORT_SYMBOL_GPL(hv_para_set_sint_proxy); + u64 __weak hv_para_get_synic_register(unsigned int reg) { return ~0ULL; diff --git a/include/asm-generic/mshyperv.h b/include/asm-generic/mshyperv.h index c010059f1518..3955ba6d60b8 100644 --- a/include/asm-generic/mshyperv.h +++ b/include/asm-generic/mshyperv.h @@ -298,6 +298,7 @@ bool hv_is_isolation_supported(void); bool hv_isolation_type_snp(void); u64 hv_ghcb_hypercall(u64 control, void *input, void *output, u32 input_si= ze); u64 hv_tdx_hypercall(u64 control, u64 param1, u64 param2); +void hv_para_set_sint_proxy(bool enable); u64 hv_para_get_synic_register(unsigned int reg); void hv_para_set_synic_register(unsigned int reg, u64 val); void hyperv_cleanup(void); --=20 2.43.0