Blame SOURCES/kvm-KVM-x86-workaround-invalid-CPUID-0xD-9-info-on-some-.patch

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From ea5299b5dde7d0b6b2f93cb646e6a24c9f105466 Mon Sep 17 00:00:00 2001
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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Wed, 23 Mar 2022 12:33:25 +0100
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Subject: [PATCH 13/24] KVM: x86: workaround invalid CPUID[0xD,9] info on some
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 AMD processors
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Paul Lai <plai@redhat.com>
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RH-MergeRequest: 176: Enable KVM AMX support
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RH-Commit: [13/13] 38f147c911258e84e01336271ebd23a1c24371fc
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RH-Bugzilla: 1916415
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RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
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RH-Acked-by: Igor Mammedov <imammedo@redhat.com>
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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Some AMD processors expose the PKRU extended save state even if they do not have
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the related PKU feature in CPUID.  Worse, when they do they report a size of
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64, whereas the expected size of the PKRU extended save state is 8, therefore
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the esa->size == eax assertion does not hold.
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The state is already ignored by KVM_GET_SUPPORTED_CPUID because it
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was not enabled in the host XCR0.  However, QEMU kvm_cpu_xsave_init()
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runs before QEMU invokes arch_prctl() to enable dynamically-enabled
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save states such as XTILEDATA, and KVM_GET_SUPPORTED_CPUID hides save
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states that have yet to be enabled.  Therefore, kvm_cpu_xsave_init()
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needs to consult the host CPUID instead of KVM_GET_SUPPORTED_CPUID,
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and dies with an assertion failure.
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When setting up the ExtSaveArea array to match the host, ignore features that
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KVM does not report as supported.  This will cause QEMU to skip the incorrect
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CPUID leaf instead of tripping the assertion.
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Closes: https://gitlab.com/qemu-project/qemu/-/issues/916
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Reported-by: Daniel P. Berrangé <berrange@redhat.com>
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Analyzed-by: Yang Zhong <yang.zhong@intel.com>
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Reported-by: Peter Krempa <pkrempa@redhat.com>
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Tested-by: Daniel P. Berrangé <berrange@redhat.com>
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Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
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(cherry picked from commit 58f7db26f21c690cf9a669c314cfd7371506084a)
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Signed-off-by: Paul Lai <plai@redhat.com>
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---
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 target/i386/cpu.c         |  4 ++--
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 target/i386/cpu.h         |  2 ++
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 target/i386/kvm/kvm-cpu.c | 19 ++++++++++++-------
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 3 files changed, 16 insertions(+), 9 deletions(-)
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diff --git a/target/i386/cpu.c b/target/i386/cpu.c
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index 09e08f7f38..0543b846ff 100644
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--- a/target/i386/cpu.c
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+++ b/target/i386/cpu.c
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@@ -4980,8 +4980,8 @@ CpuDefinitionInfoList *qmp_query_cpu_definitions(Error **errp)
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     return cpu_list;
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 }
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-static uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
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-                                                   bool migratable_only)
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+uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
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+                                            bool migratable_only)
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 {
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     FeatureWordInfo *wi = &feature_word_info[w];
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     uint64_t r = 0;
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diff --git a/target/i386/cpu.h b/target/i386/cpu.h
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index 8ab2a4042a..006b735fe4 100644
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--- a/target/i386/cpu.h
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+++ b/target/i386/cpu.h
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@@ -604,6 +604,8 @@ typedef enum FeatureWord {
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 } FeatureWord;
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 typedef uint64_t FeatureWordArray[FEATURE_WORDS];
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+uint64_t x86_cpu_get_supported_feature_word(FeatureWord w,
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+                                            bool migratable_only);
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 /* cpuid_features bits */
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 #define CPUID_FP87 (1U << 0)
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diff --git a/target/i386/kvm/kvm-cpu.c b/target/i386/kvm/kvm-cpu.c
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index bdc967c484..74c1396a93 100644
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--- a/target/i386/kvm/kvm-cpu.c
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+++ b/target/i386/kvm/kvm-cpu.c
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@@ -99,13 +99,18 @@ static void kvm_cpu_xsave_init(void)
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     for (i = XSTATE_SSE_BIT + 1; i < XSAVE_STATE_AREA_COUNT; i++) {
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         ExtSaveArea *esa = &x86_ext_save_areas[i];
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-        if (esa->size) {
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-            host_cpuid(0xd, i, &eax, &ebx, &ecx, &edx;;
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-            if (eax != 0) {
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-                assert(esa->size == eax);
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-                esa->offset = ebx;
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-                esa->ecx = ecx;
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-            }
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+        if (!esa->size) {
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+            continue;
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+        }
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+        if ((x86_cpu_get_supported_feature_word(esa->feature, false) & esa->bits)
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+            != esa->bits) {
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+            continue;
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+        }
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+        host_cpuid(0xd, i, &eax, &ebx, &ecx, &edx;;
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+        if (eax != 0) {
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+            assert(esa->size == eax);
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+            esa->offset = ebx;
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+            esa->ecx = ecx;
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         }
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     }
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 }
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-- 
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2.35.3
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