qemu x86 CPUID leafs override

Commit Message

Borislav Petkov Nov. 23, 2017, 1:13 p.m. UTC

Hi guys,

I'm using the hack below to do some quick kernel testing by setting
arbitrary feature bits and then make it execute the code for that
feature.

For example, boot with:

-cpu EPYC,cpuid-leaf=0x80000007,ebx=0xf

to set some RAS feature bits and test newer RAS code.

Would something like that be of interest to a wider audience?

It is rough and ugly but if deemed useful, I could try to clean it up.

Thx.

---

Comments

[e-mail] Nov. 23, 2017, 1:18 p.m. UTC | #1

Hi,

This series seems to have some coding style problems. See output below for
more information:

Subject: [Qemu-devel] qemu x86 CPUID leafs override
Type: series
Message-id: [e-mail]

=== TEST SCRIPT BEGIN ===
#!/bin/bash

BASE=base
n=1
total=$(git log --oneline $BASE.. | wc -l)
failed=0

git config --local diff.renamelimit 0
git config --local diff.renames True

commits="$(git log --format=%H --reverse $BASE..)"
for c in $commits; do
    echo "Checking PATCH $n/$total: $(git log -n 1 --format=%s $c)..."
    if ! git show $c --format=email | ./scripts/checkpatch.pl --mailback -; then
        failed=1
        echo
    fi
    n=$((n+1))
done

exit $failed
=== TEST SCRIPT END ===

Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
From https://github.com/patchew-project/qemu
 t [tag update]            patchew/[e-mail] -> patchew/[e-mail]
 * [new tag]               patchew/[e-mail] -> patchew/[e-mail]
Switched to a new branch 'test'
e148d5c86c qemu x86 CPUID leafs override

=== OUTPUT BEGIN ===
Checking PATCH 1/1: qemu x86 CPUID leafs override...
ERROR: code indent should never use tabs
#39: FILE: target/i386/cpu.c:2740:
+^I    env->cpuid_xlevel = cpu->cpuid_leaf;$

ERROR: code indent should never use tabs
#52: FILE: target/i386/cpu.c:3154:
+^I    if (cpu->eax)$

ERROR: braces {} are necessary for all arms of this statement
#52: FILE: target/i386/cpu.c:3154:
+	    if (cpu->eax)
[...]

ERROR: code indent should never use tabs
#53: FILE: target/i386/cpu.c:3155:
+^I^I    *eax = cpu->eax;$

ERROR: code indent should never use tabs
#55: FILE: target/i386/cpu.c:3157:
+^I    if (cpu->ebx)$

ERROR: braces {} are necessary for all arms of this statement
#55: FILE: target/i386/cpu.c:3157:
+	    if (cpu->ebx)
[...]

ERROR: code indent should never use tabs
#56: FILE: target/i386/cpu.c:3158:
+^I^I    *ebx = cpu->ebx;$

ERROR: code indent should never use tabs
#58: FILE: target/i386/cpu.c:3160:
+^I    if (cpu->ecx)$

ERROR: braces {} are necessary for all arms of this statement
#58: FILE: target/i386/cpu.c:3160:
+	    if (cpu->ecx)
[...]

ERROR: code indent should never use tabs
#59: FILE: target/i386/cpu.c:3161:
+^I^I    *ecx = cpu->ecx;$

ERROR: code indent should never use tabs
#61: FILE: target/i386/cpu.c:3163:
+^I    if (cpu->edx)$

ERROR: braces {} are necessary for all arms of this statement
#61: FILE: target/i386/cpu.c:3163:
+	    if (cpu->edx)
[...]

ERROR: code indent should never use tabs
#62: FILE: target/i386/cpu.c:3164:
+^I^I    *edx = cpu->edx;$

ERROR: Missing Signed-off-by: line(s)

total: 14 errors, 0 warnings, 59 lines checked

Your patch has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

=== OUTPUT END ===

Test command exited with code: 1


---
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Patch

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 045d66191f28..249fb23be696 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -2732,6 +2732,13 @@  void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
     uint32_t limit;
     uint32_t signature[3];
 
+    /*
+     * Pull up max xlevel in case the one we've specified on the cmdline is
+     * higher.
+     */
+    if (cpu->cpuid_leaf && env->cpuid_xlevel < cpu->cpuid_leaf)
+	    env->cpuid_xlevel = cpu->cpuid_leaf;
+
     /* Calculate & apply limits for different index ranges */
     if (index >= 0xC0000000) {
         limit = env->cpuid_xlevel2;
@@ -3140,6 +3147,22 @@  void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         *edx = 0;
         break;
     }
+
+    /* Do CPUID overrides: */
+    if (cpu->cpuid_leaf && cpu->cpuid_leaf == index) {
+
+	    if (cpu->eax)
+		    *eax = cpu->eax;
+
+	    if (cpu->ebx)
+		    *ebx = cpu->ebx;
+
+	    if (cpu->ecx)
+		    *ecx = cpu->ecx;
+
+	    if (cpu->edx)
+		    *edx = cpu->edx;
+    }
 }
 
 /* CPUClass::reset() */
@@ -4173,6 +4196,11 @@  static Property x86_cpu_properties[] = {
      * to the specific Windows version being used."
      */
     DEFINE_PROP_INT32("x-hv-max-vps", X86CPU, hv_max_vps, -1),
+    DEFINE_PROP_UINT32("cpuid-leaf", X86CPU, cpuid_leaf, UINT32_MAX),
+    DEFINE_PROP_UINT32("eax", X86CPU, eax, UINT32_MAX),
+    DEFINE_PROP_UINT32("ebx", X86CPU, ebx, UINT32_MAX),
+    DEFINE_PROP_UINT32("ecx", X86CPU, ecx, UINT32_MAX),
+    DEFINE_PROP_UINT32("edx", X86CPU, edx, UINT32_MAX),
     DEFINE_PROP_END_OF_LIST()
 };
 
diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index b086b1528b89..b336b0849456 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1284,6 +1284,13 @@  struct X86CPU {
     int32_t thread_id;
 
     int32_t hv_max_vps;
+
+    /*
+     * CPUID overrides:
+     */
+    uint32_t cpuid_leaf;
+    uint32_t eax, ebx, ecx, edx;
+
 };
 
 static inline X86CPU *x86_env_get_cpu(CPUX86State *env)