From: Michael Roth <michael.roth@amd.com>
To: qemu-devel@nongnu.org
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
Eduardo Habkost <ehabkost@redhat.com>,
Richard Henderson <richard.henderson@linaro.org>,
Igor Mammedov <imammedo@redhat.com>,
zhenwei pi <pizhenwei@bytedance.com>
Subject: [PATCH] target/i386: suppress CPUID leaves not defined by the CPU vendor
Date: Wed, 7 Jul 2021 19:36:23 -0500 [thread overview]
Message-ID: <20210708003623.18665-1-michael.roth@amd.com> (raw)
Currently all built-in CPUs report cache information via CPUID leaves 2
and 4, but these have never been defined for AMD. In the case of
SEV-SNP this can cause issues with CPUID enforcement. Address this by
allowing CPU types to suppress these via a new "x-vendor-cpuid-only"
CPU property, which is true by default, but switched off for older
machine types to maintain compatibility.
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Igor Mammedov <imammedo@redhat.com>
Cc: zhenwei pi <pizhenwei@bytedance.com>
Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
hw/i386/pc.c | 1 +
target/i386/cpu.c | 6 ++++++
target/i386/cpu.h | 3 +++
3 files changed, 10 insertions(+)
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 8e1220db72..aa79c5e0e6 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -98,6 +98,7 @@ GlobalProperty pc_compat_6_0[] = {
{ "qemu64" "-" TYPE_X86_CPU, "family", "6" },
{ "qemu64" "-" TYPE_X86_CPU, "model", "6" },
{ "qemu64" "-" TYPE_X86_CPU, "stepping", "3" },
+ { TYPE_X86_CPU, "x-vendor-cpuid-only", "off" },
};
const size_t pc_compat_6_0_len = G_N_ELEMENTS(pc_compat_6_0);
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 5f595a0d7e..0b6c921e5a 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -5155,6 +5155,9 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
if (cpu->cache_info_passthrough) {
host_cpuid(index, 0, eax, ebx, ecx, edx);
break;
+ } else if (cpu->vendor_cpuid_only && IS_AMD_CPU(env)) {
+ *eax = *ebx = *ecx = *edx = 0;
+ break;
}
*eax = 1; /* Number of CPUID[EAX=2] calls required */
*ebx = 0;
@@ -5176,6 +5179,8 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
if ((*eax & 31) && cs->nr_cores > 1) {
*eax |= (cs->nr_cores - 1) << 26;
}
+ } else if (cpu->vendor_cpuid_only && IS_AMD_CPU(env)) {
+ *eax = *ebx = *ecx = *edx = 0;
} else {
*eax = 0;
switch (count) {
@@ -6647,6 +6652,7 @@ static Property x86_cpu_properties[] = {
DEFINE_PROP_BOOL("full-cpuid-auto-level", X86CPU, full_cpuid_auto_level, true),
DEFINE_PROP_STRING("hv-vendor-id", X86CPU, hyperv_vendor),
DEFINE_PROP_BOOL("cpuid-0xb", X86CPU, enable_cpuid_0xb, true),
+ DEFINE_PROP_BOOL("x-vendor-cpuid-only", X86CPU, vendor_cpuid_only, true),
DEFINE_PROP_BOOL("lmce", X86CPU, enable_lmce, false),
DEFINE_PROP_BOOL("l3-cache", X86CPU, enable_l3_cache, true),
DEFINE_PROP_BOOL("kvm-no-smi-migration", X86CPU, kvm_no_smi_migration,
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 0f7ddbfeae..c4152634e7 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1746,6 +1746,9 @@ struct X86CPU {
/* Enable auto level-increase for all CPUID leaves */
bool full_cpuid_auto_level;
+ /* Only advertise CPUID leaves defined by the vendor */
+ bool vendor_cpuid_only;
+
/* Enable auto level-increase for Intel Processor Trace leave */
bool intel_pt_auto_level;
--
2.25.1
next reply other threads:[~2021-07-08 0:43 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-08 0:36 Michael Roth [this message]
2021-07-08 17:06 ` [PATCH] target/i386: Fix cpuid level for AMD Michael Roth
2021-07-08 21:05 ` Eduardo Habkost
2021-07-08 21:05 ` [PATCH] target/i386: suppress CPUID leaves not defined by the CPU vendor Eduardo Habkost
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