The logic of figuring out whether CMCI is supported is broken, causing
the CMCI accessing tests to fail on Skylake bare-metal.
Determine whether CMCI is supported according to the maximum entries in
the LVT as encoded in the APIC version register.
Suggested-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
Signed-off-by: Nadav Amit <namit@xxxxxxxxxx>
---
lib/x86/apic.h | 7 +++++++
x86/vmx_tests.c | 10 +---------
2 files changed, 8 insertions(+), 9 deletions(-)
diff --git a/lib/x86/apic.h b/lib/x86/apic.h
index b5bf208..a7eff63 100644
--- a/lib/x86/apic.h
+++ b/lib/x86/apic.h
@@ -70,6 +70,11 @@ static inline u32 x2apic_msr(u32 reg)
return APIC_BASE_MSR + (reg >> 4);
}
+static inline bool apic_lvt_entry_supported(int idx)
+{
+ return GET_APIC_MAXLVT(apic_read(APIC_LVR)) >= idx;
+}
+
static inline bool x2apic_reg_reserved(u32 reg)
{
switch (reg) {
@@ -83,6 +88,8 @@ static inline bool x2apic_reg_reserved(u32 reg)
case 0x3a0 ... 0x3d0:
case 0x3f0:
return true;
+ case APIC_CMCI:
+ return !apic_lvt_entry_supported(6);
default:
return false;
}
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index f4b348b..0c710cd 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -5863,11 +5863,6 @@ static u64 virt_x2apic_mode_nibble1(u64 val)
return val & 0xf0;
}
-static bool is_cmci_enabled(void)
-{
- return rdmsr(MSR_IA32_MCG_CAP) & BIT_ULL(10);
-}
-
static void virt_x2apic_mode_rd_expectation(
u32 reg, bool virt_x2apic_mode_on, bool disable_x2apic,
bool apic_register_virtualization, bool virtual_interrupt_delivery,
@@ -5877,9 +5872,6 @@ static void virt_x2apic_mode_rd_expectation(
!x2apic_reg_reserved(reg) &&
reg != APIC_EOI;
- if (reg == APIC_CMCI && !is_cmci_enabled())
- readable = false;
-
expectation->rd_exit_reason = VMX_VMCALL;
expectation->virt_fn = virt_x2apic_mode_identity;
if (virt_x2apic_mode_on && apic_register_virtualization) {
@@ -5943,7 +5935,7 @@ static bool get_x2apic_wr_val(u32 reg, u64 *val)
*val = apic_read(reg);
break;
case APIC_CMCI:
- if (!is_cmci_enabled())
+ if (!apic_lvt_entry_supported(6))
return false;
*val = apic_read(reg);
break;
--
2.17.1
