[PATCH v3 03/14] x86/svm: Cleanup selective cr0 write intercept test

Yosry Ahmed posted 14 patches 2 months, 4 weeks ago
[PATCH v3 03/14] x86/svm: Cleanup selective cr0 write intercept test
Posted by Yosry Ahmed 2 months, 4 weeks ago
Rename the test and functions to more general names describing the test
more accurately. Use X86_CR0_CD instead of hardcoding the bitmask, and
explicitly clear the bit in the prepare() function to make it clearer
that it would only be set by the test.

Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
---
 x86/svm_tests.c | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

diff --git a/x86/svm_tests.c b/x86/svm_tests.c
index 80d5aeb108650..e911659194b3d 100644
--- a/x86/svm_tests.c
+++ b/x86/svm_tests.c
@@ -793,23 +793,19 @@ static bool check_asid_zero(struct svm_test *test)
 	return vmcb->control.exit_code == SVM_EXIT_ERR;
 }
 
-static void sel_cr0_bug_prepare(struct svm_test *test)
+static void prepare_sel_cr0_intercept(struct svm_test *test)
 {
+	vmcb->save.cr0 &= ~X86_CR0_CD;
 	vmcb->control.intercept |= (1ULL << INTERCEPT_SELECTIVE_CR0);
 }
 
-static bool sel_cr0_bug_finished(struct svm_test *test)
-{
-	return true;
-}
-
-static void sel_cr0_bug_test(struct svm_test *test)
+static void test_sel_cr0_write_intercept(struct svm_test *test)
 {
 	unsigned long cr0;
 
-	/* read cr0, clear CD, and write back */
+	/* read cr0, set CD, and write back */
 	cr0  = read_cr0();
-	cr0 |= (1UL << 30);
+	cr0 |= X86_CR0_CD;
 	write_cr0(cr0);
 
 	/*
@@ -821,7 +817,7 @@ static void sel_cr0_bug_test(struct svm_test *test)
 	exit(report_summary());
 }
 
-static bool sel_cr0_bug_check(struct svm_test *test)
+static bool check_sel_cr0_intercept(struct svm_test *test)
 {
 	return vmcb->control.exit_code == SVM_EXIT_CR0_SEL_WRITE;
 }
@@ -3486,9 +3482,9 @@ struct svm_test svm_tests[] = {
 	{ "asid_zero", default_supported, prepare_asid_zero,
 	  default_prepare_gif_clear, test_asid_zero,
 	  default_finished, check_asid_zero },
-	{ "sel_cr0_bug", default_supported, sel_cr0_bug_prepare,
-	  default_prepare_gif_clear, sel_cr0_bug_test,
-	  sel_cr0_bug_finished, sel_cr0_bug_check },
+	{ "sel cr0 write intercept", default_supported,
+	  prepare_sel_cr0_intercept, default_prepare_gif_clear,
+	  test_sel_cr0_write_intercept, default_finished, check_sel_cr0_intercept},
 	{ "tsc_adjust", tsc_adjust_supported, tsc_adjust_prepare,
 	  default_prepare_gif_clear, tsc_adjust_test,
 	  default_finished, tsc_adjust_check },
-- 
2.51.2.1041.gc1ab5b90ca-goog
Re: [PATCH v3 03/14] x86/svm: Cleanup selective cr0 write intercept test
Posted by Manali Shukla 2 months, 4 weeks ago
On 11/11/2025 4:56 AM, Yosry Ahmed wrote:
> Rename the test and functions to more general names describing the test
> more accurately. Use X86_CR0_CD instead of hardcoding the bitmask, and
> explicitly clear the bit in the prepare() function to make it clearer
> that it would only be set by the test.
> 
> Signed-off-by: Yosry Ahmed <yosry.ahmed@linux.dev>
> ---
>  x86/svm_tests.c | 22 +++++++++-------------
>  1 file changed, 9 insertions(+), 13 deletions(-)
> 
> diff --git a/x86/svm_tests.c b/x86/svm_tests.c
> index 80d5aeb108650..e911659194b3d 100644
> --- a/x86/svm_tests.c
> +++ b/x86/svm_tests.c
> @@ -793,23 +793,19 @@ static bool check_asid_zero(struct svm_test *test)
>  	return vmcb->control.exit_code == SVM_EXIT_ERR;
>  }
>  
> -static void sel_cr0_bug_prepare(struct svm_test *test)
> +static void prepare_sel_cr0_intercept(struct svm_test *test)
>  {
> +	vmcb->save.cr0 &= ~X86_CR0_CD;
>  	vmcb->control.intercept |= (1ULL << INTERCEPT_SELECTIVE_CR0);
>  }
>  
> -static bool sel_cr0_bug_finished(struct svm_test *test)
> -{
> -	return true;
> -}
> -
> -static void sel_cr0_bug_test(struct svm_test *test)
> +static void test_sel_cr0_write_intercept(struct svm_test *test)
>  {
>  	unsigned long cr0;
>  
> -	/* read cr0, clear CD, and write back */
> +	/* read cr0, set CD, and write back */
>  	cr0  = read_cr0();
> -	cr0 |= (1UL << 30);
> +	cr0 |= X86_CR0_CD;
>  	write_cr0(cr0);
>  
>  	/*
> @@ -821,7 +817,7 @@ static void sel_cr0_bug_test(struct svm_test *test)
>  	exit(report_summary());
>  }
>  
> -static bool sel_cr0_bug_check(struct svm_test *test)
> +static bool check_sel_cr0_intercept(struct svm_test *test)
>  {
>  	return vmcb->control.exit_code == SVM_EXIT_CR0_SEL_WRITE;
>  }
> @@ -3486,9 +3482,9 @@ struct svm_test svm_tests[] = {
>  	{ "asid_zero", default_supported, prepare_asid_zero,
>  	  default_prepare_gif_clear, test_asid_zero,
>  	  default_finished, check_asid_zero },
> -	{ "sel_cr0_bug", default_supported, sel_cr0_bug_prepare,
> -	  default_prepare_gif_clear, sel_cr0_bug_test,
> -	  sel_cr0_bug_finished, sel_cr0_bug_check },
> +	{ "sel cr0 write intercept", default_supported,
> +	  prepare_sel_cr0_intercept, default_prepare_gif_clear,
> +	  test_sel_cr0_write_intercept, default_finished, check_sel_cr0_intercept},
>  	{ "tsc_adjust", tsc_adjust_supported, tsc_adjust_prepare,
>  	  default_prepare_gif_clear, tsc_adjust_test,
>  	  default_finished, tsc_adjust_check },


LGTM

Reviewed-by: Manali Shukla <manali.shukla@amd.com>

Tested on AMD Genoa machine. This test case works as expected.

Tested-by: Manali Shukla <manali.shukla@amd.com>