[4/4,v3,kvm-unit-test,nVMX] : Check "load IA32_PAT" on vmentry of L2 guests
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Message ID 20190403215905.2474-5-krish.sadhukhan@oracle.com
State New
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  • [1/4,v3,nVMX] : Check "load IA32_PAT" VM-exit control on vmentry
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Commit Message

Krish Sadhukhan April 3, 2019, 9:59 p.m. UTC
.to verify KVM performs the appropriate consistency checks for loading
IA32_PAT as part of running a nested guest.

According to section "Checks on Host Control Registers and MSRs" in Intel
SDM vol 3C, the following check is performed on vmentry:

    If the “load IA32_PAT” VM-exit control is 1, the value of the field
    for the IA32_PAT MSR must be one that could be written by WRMSR
    without fault at CPL 0. Specifically, each of the 8 bytes in the
    field must have one of the values 0 (UC), 1 (WC), 4 (WT), 5 (WP),
    6 (WB), or 7 (UC-).

Since a PAT value higher than 8 will yield the same test result as that
of 8, we want to confine our tests only up to 8 in order to reduce
redundancy of tests and to avoid too many vmentries.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
Reviewed-by: Karl Heubaum <karl.heubaum@oracle.com>
---
 x86/vmx_tests.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 71 insertions(+)

Comments

Sean Christopherson April 4, 2019, 4:10 p.m. UTC | #1
On Wed, Apr 03, 2019 at 05:59:05PM -0400, Krish Sadhukhan wrote:
> .to verify KVM performs the appropriate consistency checks for loading
> IA32_PAT as part of running a nested guest.
> 
> According to section "Checks on Host Control Registers and MSRs" in Intel
> SDM vol 3C, the following check is performed on vmentry:
> 
>     If the “load IA32_PAT” VM-exit control is 1, the value of the field
>     for the IA32_PAT MSR must be one that could be written by WRMSR
>     without fault at CPL 0. Specifically, each of the 8 bytes in the
>     field must have one of the values 0 (UC), 1 (WC), 4 (WT), 5 (WP),
>     6 (WB), or 7 (UC-).
> 
> Since a PAT value higher than 8 will yield the same test result as that
> of 8, we want to confine our tests only up to 8 in order to reduce
> redundancy of tests and to avoid too many vmentries.
> 
> Signed-off-by: Krish Sadhukhan <krish.sadhukhan@oracle.com>
> Reviewed-by: Karl Heubaum <karl.heubaum@oracle.com>
> ---
>  x86/vmx_tests.c | 71 +++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 71 insertions(+)
> 
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index 66a87f6..04b1aee 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -4995,6 +4995,75 @@ static void test_sysenter_field(u32 field, const char *name)
>  	vmcs_write(field, addr_saved);
>  }
>  
> +/*
> + * Since a PAT value higher than 8 will yield the same test result as that
> + * of 8, we want to confine our tests only up to 8 in order to reduce
> + * redundancy of tests and to avoid too many vmentries.
> + */
> +#define	PAT_VAL_LIMIT	8
> +
> +static void test_pat(u32 fld, const char * fld_name, u32 ctrl_fld, u64 ctrl_bit)

Please spell out "field" in all cases.  Saving a few characters is not
worth the extra mental gymnastics required when reading the code.  There
are zero hits for "fld" in KVM or kvm-unit-tests, and hundreds of hits
for "field".

> +{
> +	u32 ctrl_saved = vmcs_read(ctrl_fld);
> +	u64 pat_saved = vmcs_read(fld);
> +	u64 i, val;
> +	u32 j;
> +	int error;
> +
> +	vmcs_write(ctrl_fld, ctrl_saved & ~ctrl_bit);
> +	for (i = 0; i <= PAT_VAL_LIMIT; i++) {
> +		/* Test PAT0..PAT7 fields */
> +		for (j = 0; j < 8; j++) {
> +			val = i << j * 8;
> +			vmcs_write(fld, val);
> +			report_prefix_pushf("%s %lx", fld_name, val);
> +			test_vmx_vmlaunch(0, false);
> +			report_prefix_pop();
> +		}
> +	}
> +
> +	vmcs_write(ctrl_fld, ctrl_saved | ctrl_bit);
> +	for (i = 0; i <= PAT_VAL_LIMIT; i++) {
> +		/* Test PAT0..PAT7 fields */
> +		for (j = 0; j < 8; j++) {
> +			val = i << j * 8;
> +			vmcs_write(fld, val);
> +			report_prefix_pushf("%s %lx", fld_name, val);
> +			if (i == 0x2 || i == 0x3 || i >= 0x8)
> +				error = VMXERR_ENTRY_INVALID_HOST_STATE_FIELD;
> +			else
> +				error = 0;
> +			test_vmx_vmlaunch(error, false);
> +			report_prefix_pop();
> +		}
> +	}
> +
> +	vmcs_write(ctrl_fld, ctrl_saved);
> +	vmcs_write(fld, pat_saved);
> +}
> +
> +/*
> + *  If the "load IA32_PAT" VM-exit control is 1, the value of the field
> + *  for the IA32_PAT MSR must be one that could be written by WRMSR
> + *  without fault at CPL 0. Specifically, each of the 8 bytes in the
> + *  field must have one of the values 0 (UC), 1 (WC), 4 (WT), 5 (WP),
> + *  6 (WB), or 7 (UC-).
> + *
> + *  [Intel SDM]
> + */
> +static void test_load_host_pat(void)
> +{
> +	/*
> +	 * "load IA32_PAT" VM-exit control
> +	 */
> +	if (!(ctrl_exit_rev.clr & EXI_LOAD_PAT)) {
> +		printf("\"Load-IA32-PAT\" exit control not supported\n");
> +		return;
> +	}
> +
> +	test_pat(HOST_PAT, "HOST_PAT", EXI_CONTROLS, EXI_LOAD_PAT);
> +}
> +
>  /*
>   * Check that the virtual CPU checks the VMX Host State Area as
>   * documented in the Intel SDM.
> @@ -5010,6 +5079,8 @@ static void vmx_host_state_area_test(void)
>  
>  	test_sysenter_field(HOST_SYSENTER_ESP, "HOST_SYSENTER_ESP");
>  	test_sysenter_field(HOST_SYSENTER_EIP, "HOST_SYSENTER_EIP");
> +
> +	test_load_host_pat();
>  }
>  
>  static bool valid_vmcs_for_vmentry(void)
> -- 
> 2.17.2
>

Patch
diff mbox series

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index 66a87f6..04b1aee 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -4995,6 +4995,75 @@  static void test_sysenter_field(u32 field, const char *name)
 	vmcs_write(field, addr_saved);
 }
 
+/*
+ * Since a PAT value higher than 8 will yield the same test result as that
+ * of 8, we want to confine our tests only up to 8 in order to reduce
+ * redundancy of tests and to avoid too many vmentries.
+ */
+#define	PAT_VAL_LIMIT	8
+
+static void test_pat(u32 fld, const char * fld_name, u32 ctrl_fld, u64 ctrl_bit)
+{
+	u32 ctrl_saved = vmcs_read(ctrl_fld);
+	u64 pat_saved = vmcs_read(fld);
+	u64 i, val;
+	u32 j;
+	int error;
+
+	vmcs_write(ctrl_fld, ctrl_saved & ~ctrl_bit);
+	for (i = 0; i <= PAT_VAL_LIMIT; i++) {
+		/* Test PAT0..PAT7 fields */
+		for (j = 0; j < 8; j++) {
+			val = i << j * 8;
+			vmcs_write(fld, val);
+			report_prefix_pushf("%s %lx", fld_name, val);
+			test_vmx_vmlaunch(0, false);
+			report_prefix_pop();
+		}
+	}
+
+	vmcs_write(ctrl_fld, ctrl_saved | ctrl_bit);
+	for (i = 0; i <= PAT_VAL_LIMIT; i++) {
+		/* Test PAT0..PAT7 fields */
+		for (j = 0; j < 8; j++) {
+			val = i << j * 8;
+			vmcs_write(fld, val);
+			report_prefix_pushf("%s %lx", fld_name, val);
+			if (i == 0x2 || i == 0x3 || i >= 0x8)
+				error = VMXERR_ENTRY_INVALID_HOST_STATE_FIELD;
+			else
+				error = 0;
+			test_vmx_vmlaunch(error, false);
+			report_prefix_pop();
+		}
+	}
+
+	vmcs_write(ctrl_fld, ctrl_saved);
+	vmcs_write(fld, pat_saved);
+}
+
+/*
+ *  If the "load IA32_PAT" VM-exit control is 1, the value of the field
+ *  for the IA32_PAT MSR must be one that could be written by WRMSR
+ *  without fault at CPL 0. Specifically, each of the 8 bytes in the
+ *  field must have one of the values 0 (UC), 1 (WC), 4 (WT), 5 (WP),
+ *  6 (WB), or 7 (UC-).
+ *
+ *  [Intel SDM]
+ */
+static void test_load_host_pat(void)
+{
+	/*
+	 * "load IA32_PAT" VM-exit control
+	 */
+	if (!(ctrl_exit_rev.clr & EXI_LOAD_PAT)) {
+		printf("\"Load-IA32-PAT\" exit control not supported\n");
+		return;
+	}
+
+	test_pat(HOST_PAT, "HOST_PAT", EXI_CONTROLS, EXI_LOAD_PAT);
+}
+
 /*
  * Check that the virtual CPU checks the VMX Host State Area as
  * documented in the Intel SDM.
@@ -5010,6 +5079,8 @@  static void vmx_host_state_area_test(void)
 
 	test_sysenter_field(HOST_SYSENTER_ESP, "HOST_SYSENTER_ESP");
 	test_sysenter_field(HOST_SYSENTER_EIP, "HOST_SYSENTER_EIP");
+
+	test_load_host_pat();
 }
 
 static bool valid_vmcs_for_vmentry(void)