On 06/17/2019 12:52 PM, Nadav Amit wrote:
On May 3, 2019, at 10:49 AM, nadav.amit@xxxxxxxxx wrote:
From: Nadav Amit <nadav.amit@xxxxxxxxx>
On EPT violation, the exit qualifications may have some undefined bits.
Bit 6 is undefined if "mode-based execute control" is 0.
Bits 9-11 are undefined unless the processor supports advanced VM-exit
information for EPT violations.
Right now on KVM these bits are always undefined inside the VM (i.e., in
an emulated VM-exit). Mask these bits to avoid potential false
indication of failures.
Signed-off-by: Nadav Amit <nadav.amit@xxxxxxxxx>
---
x86/vmx.h | 20 ++++++++++++--------
x86/vmx_tests.c | 4 ++++
2 files changed, 16 insertions(+), 8 deletions(-)
diff --git a/x86/vmx.h b/x86/vmx.h
index cc377ef..5053d6f 100644
--- a/x86/vmx.h
+++ b/x86/vmx.h
@@ -603,16 +603,20 @@ enum vm_instruction_error_number {
#define EPT_ADDR_MASK GENMASK_ULL(51, 12)
#define PAGE_MASK_2M (~(PAGE_SIZE_2M-1))
-#define EPT_VLT_RD 1
-#define EPT_VLT_WR (1 << 1)
-#define EPT_VLT_FETCH (1 << 2)
-#define EPT_VLT_PERM_RD (1 << 3)
-#define EPT_VLT_PERM_WR (1 << 4)
-#define EPT_VLT_PERM_EX (1 << 5)
+#define EPT_VLT_RD (1ull << 0)
+#define EPT_VLT_WR (1ull << 1)
+#define EPT_VLT_FETCH (1ull << 2)
+#define EPT_VLT_PERM_RD (1ull << 3)
+#define EPT_VLT_PERM_WR (1ull << 4)
+#define EPT_VLT_PERM_EX (1ull << 5)
+#define EPT_VLT_PERM_USER_EX (1ull << 6)
#define EPT_VLT_PERMS (EPT_VLT_PERM_RD | EPT_VLT_PERM_WR | \
EPT_VLT_PERM_EX)
-#define EPT_VLT_LADDR_VLD (1 << 7)
-#define EPT_VLT_PADDR (1 << 8)
+#define EPT_VLT_LADDR_VLD (1ull << 7)
+#define EPT_VLT_PADDR (1ull << 8)
+#define EPT_VLT_GUEST_USER (1ull << 9)
+#define EPT_VLT_GUEST_WR (1ull << 10)
This one should be named EPT_VLT_GUEST_RW, assuming you are naming them
according to the 1-setting of the bits.
+#define EPT_VLT_GUEST_EX (1ull << 11)
#define MAGIC_VAL_1 0x12345678ul
#define MAGIC_VAL_2 0x87654321ul
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index c52ebc6..b4129e1 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -2365,6 +2365,10 @@ static void do_ept_violation(bool leaf, enum ept_access_op op,
qual = vmcs_read(EXI_QUALIFICATION);
+ /* Mask undefined bits (which may later be defined in certain cases). */
+ qual &= ~(EPT_VLT_GUEST_USER | EPT_VLT_GUEST_WR | EPT_VLT_GUEST_EX |
+ EPT_VLT_PERM_USER_EX);
+
The "DIAGNOSE" macro doesn't check any of these bits, so this masking
seems redundant.
Also, don't we need to check for the relevant conditions before masking
the bits ? For example, EPT_VLT_PERM_USER_EX is dependent on "mode-based
execute control" VM-execution control" and the other ones depend on bit
7 and 8 of the Exit Qualification field.
diagnose_ept_violation_qual(expected_qual, qual);
TEST_EXPECT_EQ(expected_qual, qual);
--
2.17.1
Ping.
