[kvm-unit-tests PATCH 0/2] Better max VMCS field index test

[kvm-unit-tests PATCH 0/2] Better max VMCS field index test

[Nadav Amit]

The first patch improves max VMCS field index search so an exact
comparison would be possible. The second one does some cleanup.

Cc: Jim Mattson <jmattson@google.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>

Nadav Amit (2):
  x86: vmx: Comprehensive max VMCS field search
  x86: vmx: Remove max_index tracking in check_vmcs_field()

 x86/vmx.c | 50 ++++++++++++++++++++++++++++++++++----------------
 1 file changed, 34 insertions(+), 16 deletions(-)

-- 
2.17.1

[kvm-unit-tests PATCH 1/2] x86: vmx: Comprehensive max VMCS field search

[Nadav Amit]

Search all VMCS fields when looking for the max VMCS field index.
Perform the search backwards to save some time. Change the existing test
to compare the maximum expected index (based on MSRs) is equal to the
actual one.  This improves the test that currently performs
greater-equal comparison.

Suggested-by: Jim Mattson <jmattson@google.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 x86/vmx.c | 38 ++++++++++++++++++++++++++++++++++----
 1 file changed, 34 insertions(+), 4 deletions(-)

diff --git a/x86/vmx.c b/x86/vmx.c
index 5803dc7..a1af59c 100644
--- a/x86/vmx.c
+++ b/x86/vmx.c
@@ -348,6 +348,34 @@ static bool check_all_vmcs_fields(u8 cookie)
 	return __check_all_vmcs_fields(cookie, NULL);
 }
 
+static u32 find_vmcs_max_index(void)
+{
+	u32 idx, width, type, enc;
+	u64 actual;
+	int ret;
+
+	/* scan backwards and stop when found */
+	for (idx = (1 << 9) - 1; idx >= 0; idx--) {
+
+		/* try all combinations of width and type */
+		for (type = 0; type < (1 << 2); type++) {
+			for (width = 0; width < (1 << 2) ; width++) {
+				enc = (idx << VMCS_FIELD_INDEX_SHIFT) |
+				      (type << VMCS_FIELD_TYPE_SHIFT) |
+				      (width << VMCS_FIELD_WIDTH_SHIFT);
+
+				ret = vmcs_read_checking(enc, &actual);
+				assert(!(ret & X86_EFLAGS_CF));
+				if (!(ret & X86_EFLAGS_ZF))
+					return idx;
+			}
+		}
+	}
+	/* some VMCS fields should exist */
+	assert(0);
+	return 0;
+}
+
 static void test_vmwrite_vmread(void)
 {
 	struct vmcs *vmcs = alloc_page();
@@ -358,11 +386,13 @@ static void test_vmwrite_vmread(void)
 	assert(!make_vmcs_current(vmcs));
 
 	set_all_vmcs_fields(0x42);
-	report(__check_all_vmcs_fields(0x42, &max_index), "VMWRITE/VMREAD");
+	report(check_all_vmcs_fields(0x42), "VMWRITE/VMREAD");
 
-	vmcs_enum_max = rdmsr(MSR_IA32_VMX_VMCS_ENUM) & VMCS_FIELD_INDEX_MASK;
-	report(vmcs_enum_max >= max_index,
-	       "VMX_VMCS_ENUM.MAX_INDEX expected at least: %x, actual: %x",
+	vmcs_enum_max = (rdmsr(MSR_IA32_VMX_VMCS_ENUM) & VMCS_FIELD_INDEX_MASK)
+			>> VMCS_FIELD_INDEX_SHIFT;
+	max_index = find_vmcs_max_index();
+	report(vmcs_enum_max == max_index,
+	       "VMX_VMCS_ENUM.MAX_INDEX expected: %x, actual: %x",
 	       max_index, vmcs_enum_max);
 
 	assert(!vmcs_clear(vmcs));
-- 
2.17.1

[kvm-unit-tests PATCH 2/2] x86: vmx: Remove max_index tracking in check_vmcs_field()

[Nadav Amit]

Now that comprehensive search for maximum VMCS field index is performed,
the tracking of the maximum index in __check_vmcs_field() is no longer
needed. Remove all the related logic accordingly.

Cc: Jim Mattson <jmattson@google.com>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
---
 x86/vmx.c | 18 +++---------------
 1 file changed, 3 insertions(+), 15 deletions(-)

diff --git a/x86/vmx.c b/x86/vmx.c
index a1af59c..8bcb438 100644
--- a/x86/vmx.c
+++ b/x86/vmx.c
@@ -281,11 +281,10 @@ static void set_vmcs_field(struct vmcs_field *f, u8 cookie)
 	vmcs_write(f->encoding, vmcs_field_value(f, cookie));
 }
 
-static bool check_vmcs_field(struct vmcs_field *f, u8 cookie, u32 *max_index)
+static bool check_vmcs_field(struct vmcs_field *f, u8 cookie)
 {
 	u64 expected;
 	u64 actual;
-	u32 index;
 	int ret;
 
 	if (f->encoding == VMX_INST_ERROR) {
@@ -299,12 +298,6 @@ static bool check_vmcs_field(struct vmcs_field *f, u8 cookie, u32 *max_index)
 	if (ret & X86_EFLAGS_ZF)
 		return true;
 
-	if (max_index) {
-		index = f->encoding & VMCS_FIELD_INDEX_MASK;
-		if (index > *max_index)
-			*max_index = index;
-	}
-
 	if (vmcs_field_readonly(f)) {
 		printf("Skipping read-only field %lx\n", f->encoding);
 		return true;
@@ -330,24 +323,19 @@ static void set_all_vmcs_fields(u8 cookie)
 		set_vmcs_field(&vmcs_fields[i], cookie);
 }
 
-static bool __check_all_vmcs_fields(u8 cookie, u32 *max_index)
+static bool check_all_vmcs_fields(u8 cookie)
 {
 	bool pass = true;
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(vmcs_fields); i++) {
-		if (!check_vmcs_field(&vmcs_fields[i], cookie, max_index))
+		if (!check_vmcs_field(&vmcs_fields[i], cookie))
 			pass = false;
 	}
 
 	return pass;
 }
 
-static bool check_all_vmcs_fields(u8 cookie)
-{
-	return __check_all_vmcs_fields(cookie, NULL);
-}
-
 static u32 find_vmcs_max_index(void)
 {
 	u32 idx, width, type, enc;
-- 
2.17.1

Re: [kvm-unit-tests PATCH 0/2] Better max VMCS field index test

[Paolo Bonzini]

On 19/12/19 11:10, Nadav Amit wrote:
> The first patch improves max VMCS field index search so an exact
> comparison would be possible. The second one does some cleanup.
> 
> Cc: Jim Mattson <jmattson@google.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> 
> Nadav Amit (2):
>   x86: vmx: Comprehensive max VMCS field search
>   x86: vmx: Remove max_index tracking in check_vmcs_field()
> 
>  x86/vmx.c | 50 ++++++++++++++++++++++++++++++++++----------------
>  1 file changed, 34 insertions(+), 16 deletions(-)
> 

Queued, thanks.

Paolo