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bh=OgjaHM7gHNQn+818N0bP1zheDu+SIctC111b5yfdnSw=; b=JyL4N0hk1NqwtGbZtwHL9ZKccGWDSz9X0gjH2zSUvbe5JRtpk2jM+Jgc8M9KLFNmQSnedq kSfv6WDSvHTcCOYLHXXm41Tu837uZZ2UUGpUumKyOril6YCV8kwyfHFK0tuLgfd5dHjkg2 tZQa+ptPm8olPsKovr1Q6y1Nwe8EaPE= X-MC-Unique: NaIny7qqO56qiWHg5a3cSw-1 From: Vitaly Kuznetsov To: qemu-devel@nongnu.org, Paolo Bonzini Cc: Marcelo Tosatti Subject: [PATCH RESEND 1/2] i386: Fix conditional CONFIG_SYNDBG enablement Date: Fri, 22 Sep 2023 14:19:14 +0200 Message-ID: <20230922121915.566591-2-vkuznets@redhat.com> In-Reply-To: <20230922121915.566591-1-vkuznets@redhat.com> References: <20230922121915.566591-1-vkuznets@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.129.124; envelope-from=vkuznets@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1695385215653100003 Content-Type: text/plain; charset="utf-8" Putting HYPERV_FEAT_SYNDBG entry under "#ifdef CONFIG_SYNDBG" in 'kvm_hyperv_properties' array is wrong: as HYPERV_FEAT_SYNDBG is not the highest feature number, the result is an empty (zeroed) entry in the array (and not a skipped entry!). hyperv_feature_supported() is designed to check that all CPUID bits are set but for a zeroed feature in 'kvm_hyperv_properties' it returns 'true' so QEMU considers HYPERV_FEAT_SYNDBG as always supported, regardless of whether KVM host actually supports it. To fix the issue, leave HYPERV_FEAT_SYNDBG's definition in 'kvm_hyperv_properties' array, there's nothing wrong in having it defined even when 'CONFIG_SYNDBG' is not set. Instead, put "hv-syndbg" CPU property under '#ifdef CONFIG_SYNDBG' to alter the existing behavior when the flag is silently skipped in !CONFIG_SYNDBG builds. Leave an 'assert' sentinel in hyperv_feature_supported() making sure there are no 'holes' or improperly defined features in 'kvm_hyperv_properties'. Fixes: d8701185f40c ("hw: hyperv: Initial commit for Synthetic Debugging de= vice") Signed-off-by: Vitaly Kuznetsov --- target/i386/cpu.c | 2 ++ target/i386/kvm/kvm.c | 11 +++++++---- 2 files changed, 9 insertions(+), 4 deletions(-) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index 2589c8e9294a..01c7e8414408 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -7840,8 +7840,10 @@ static Property x86_cpu_properties[] =3D { HYPERV_FEAT_TLBFLUSH_DIRECT, 0), DEFINE_PROP_ON_OFF_AUTO("hv-no-nonarch-coresharing", X86CPU, hyperv_no_nonarch_cs, ON_OFF_AUTO_OFF), +#ifdef CONFIG_SYNDBG DEFINE_PROP_BIT64("hv-syndbg", X86CPU, hyperv_features, HYPERV_FEAT_SYNDBG, 0), +#endif DEFINE_PROP_BOOL("hv-passthrough", X86CPU, hyperv_passthrough, false), DEFINE_PROP_BOOL("hv-enforce-cpuid", X86CPU, hyperv_enforce_cpuid, fal= se), =20 diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index af101fcdf6ff..51b381a2fbbc 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -993,7 +993,6 @@ static struct { .bits =3D HV_DEPRECATING_AEOI_RECOMMENDED} } }, -#ifdef CONFIG_SYNDBG [HYPERV_FEAT_SYNDBG] =3D { .desc =3D "Enable synthetic kernel debugger channel (hv-syndbg)", .flags =3D { @@ -1002,7 +1001,6 @@ static struct { }, .dependencies =3D BIT(HYPERV_FEAT_SYNIC) | BIT(HYPERV_FEAT_RELAXED) }, -#endif [HYPERV_FEAT_MSR_BITMAP] =3D { .desc =3D "enlightened MSR-Bitmap (hv-emsr-bitmap)", .flags =3D { @@ -1254,6 +1252,13 @@ static bool hyperv_feature_supported(CPUState *cs, i= nt feature) uint32_t func, bits; int i, reg; =20 + /* + * kvm_hyperv_properties needs to define at least one CPUID flag which + * must be used to detect the feature, it's hard to say whether it is + * supported or not otherwise. + */ + assert(kvm_hyperv_properties[feature].flags[0].func); + for (i =3D 0; i < ARRAY_SIZE(kvm_hyperv_properties[feature].flags); i+= +) { =20 func =3D kvm_hyperv_properties[feature].flags[i].func; @@ -3483,13 +3488,11 @@ static int kvm_put_msrs(X86CPU *cpu, int level) kvm_msr_entry_add(cpu, HV_X64_MSR_TSC_EMULATION_STATUS, env->msr_hv_tsc_emulation_status); } -#ifdef CONFIG_SYNDBG if (hyperv_feat_enabled(cpu, HYPERV_FEAT_SYNDBG) && has_msr_hv_syndbg_options) { kvm_msr_entry_add(cpu, HV_X64_MSR_SYNDBG_OPTIONS, hyperv_syndbg_query_options()); } -#endif } if (hyperv_feat_enabled(cpu, HYPERV_FEAT_VAPIC)) { kvm_msr_entry_add(cpu, HV_X64_MSR_APIC_ASSIST_PAGE, --=20 2.41.0 From nobody Tue May 14 04:57:28 2024 Delivered-To: importer@patchew.org Authentication-Results: mx.zohomail.com; dkim=pass; spf=pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; 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Fri, 22 Sep 2023 08:19:19 -0400 Received: from smtp.corp.redhat.com (int-mx09.intmail.prod.int.rdu2.redhat.com [10.11.54.9]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7A6F1280D58A for ; Fri, 22 Sep 2023 12:19:19 +0000 (UTC) Received: from fedora.redhat.com (unknown [10.45.225.101]) by smtp.corp.redhat.com (Postfix) with ESMTP id C457D711291; Fri, 22 Sep 2023 12:19:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1695385161; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=J9NRn7HoslbcYQajMTe7ud5tpZSjR8KjTHMmKv/0PHE=; b=G9RePsjzMEkvRLpZHJgWUAQ4w0a+MiSGXrsvFaKp/sJk2aHKLu3GB8v1y6u1VzgtGOeYJv y+EsjKeBP+7zkINOfxVMsfuW/qPdnRlS0E4qLFI/V8s+3hDZCdZT/X+EJyoj3MFyVT7ntf sPw0GXKRvVDTpiQ/OsmSivyVNnT5VC8= X-MC-Unique: 75kclpzAOX6HUE17uSCrtw-1 From: Vitaly Kuznetsov To: qemu-devel@nongnu.org, Paolo Bonzini Cc: Marcelo Tosatti Subject: [PATCH RESEND 2/2] i386: Exclude 'hv-syndbg' from 'hv-passthrough' Date: Fri, 22 Sep 2023 14:19:15 +0200 Message-ID: <20230922121915.566591-3-vkuznets@redhat.com> In-Reply-To: <20230922121915.566591-1-vkuznets@redhat.com> References: <20230922121915.566591-1-vkuznets@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; envelope-from=vkuznets@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: 12 X-Spam_score: 1.2 X-Spam_bar: + X-Spam_report: (1.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_SBL_CSS=3.335, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1695385208412100001 Content-Type: text/plain; charset="utf-8" Windows with Hyper-V role enabled doesn't boot with 'hv-passthrough' when no debugger is configured, this significantly limits the usefulness of the feature as there's no support for subtracting Hyper-V features from CPU flags at this moment (e.g. "-cpu host,hv-passthrough,-hv-syndbg" does not work). While this is also theoretically fixable, 'hv-syndbg' is likely very special and unneeded in the default set. Genuine Hyper-V doesn't seem to enable it either. Introduce 'skip_passthrough' flag to 'kvm_hyperv_properties' and use it as one-off to skip 'hv-syndbg' when enabling features in 'hv-passthrough' mode. Note, "-cpu host,hv-passthrough,hv-syndbg" can still be used if needed. As both 'hv-passthrough' and 'hv-syndbg' are debug features, the change should not have any effect on production environments. Signed-off-by: Vitaly Kuznetsov --- docs/system/i386/hyperv.rst | 13 +++++++++---- target/i386/kvm/kvm.c | 7 +++++-- 2 files changed, 14 insertions(+), 6 deletions(-) diff --git a/docs/system/i386/hyperv.rst b/docs/system/i386/hyperv.rst index 2505dc4c86e0..009947e39141 100644 --- a/docs/system/i386/hyperv.rst +++ b/docs/system/i386/hyperv.rst @@ -262,14 +262,19 @@ Supplementary features ``hv-passthrough`` In some cases (e.g. during development) it may make sense to use QEMU in 'pass-through' mode and give Windows guests all enlightenments currently - supported by KVM. This pass-through mode is enabled by "hv-passthrough" = CPU - flag. + supported by KVM. =20 Note: ``hv-passthrough`` flag only enables enlightenments which are know= n to QEMU (have corresponding 'hv-' flag) and copies ``hv-spinlocks`` and ``hv-ven= dor-id`` values from KVM to QEMU. ``hv-passthrough`` overrides all other 'hv-' se= ttings on - the command line. Also, enabling this flag effectively prevents migratio= n as the - list of enabled enlightenments may differ between target and destination= hosts. + the command line. + + Note: ``hv-passthrough`` does not enable ``hv-syndbg`` which can prevent= certain + Windows guests from booting when used without proper configuration. If n= eeded, + ``hv-syndbg`` can be enabled additionally. + + Note: ``hv-passthrough`` effectively prevents migration as the list of e= nabled + enlightenments may differ between target and destination hosts. =20 ``hv-enforce-cpuid`` By default, KVM allows the guest to use all currently supported Hyper-V diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c index 51b381a2fbbc..cfb24ba87df5 100644 --- a/target/i386/kvm/kvm.c +++ b/target/i386/kvm/kvm.c @@ -871,6 +871,7 @@ static struct { uint32_t bits; } flags[2]; uint64_t dependencies; + bool skip_passthrough; } kvm_hyperv_properties[] =3D { [HYPERV_FEAT_RELAXED] =3D { .desc =3D "relaxed timing (hv-relaxed)", @@ -999,7 +1000,8 @@ static struct { {.func =3D HV_CPUID_FEATURES, .reg =3D R_EDX, .bits =3D HV_FEATURE_DEBUG_MSRS_AVAILABLE} }, - .dependencies =3D BIT(HYPERV_FEAT_SYNIC) | BIT(HYPERV_FEAT_RELAXED) + .dependencies =3D BIT(HYPERV_FEAT_SYNIC) | BIT(HYPERV_FEAT_RELAXED= ), + .skip_passthrough =3D true, }, [HYPERV_FEAT_MSR_BITMAP] =3D { .desc =3D "enlightened MSR-Bitmap (hv-emsr-bitmap)", @@ -1408,7 +1410,8 @@ bool kvm_hyperv_expand_features(X86CPU *cpu, Error **= errp) * hv_build_cpuid_leaf() uses this info to build guest CPUIDs. */ for (feat =3D 0; feat < ARRAY_SIZE(kvm_hyperv_properties); feat++)= { - if (hyperv_feature_supported(cs, feat)) { + if (hyperv_feature_supported(cs, feat) && + !kvm_hyperv_properties[feat].skip_passthrough) { cpu->hyperv_features |=3D BIT(feat); } } --=20 2.41.0