Add test coverage to verify MSR_IA32_FLUSH_CMD is write-only, that it can
be written with '0' (nop command) and '1' (L1D flush command) when the L1D
flush command is suported, and that writing any other bit (1-63) triggers
a #GP due to the bits/commands being reserved.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
lib/x86/msr.h | 3 +++
lib/x86/processor.h | 1 +
x86/msr.c | 11 +++++++++++
3 files changed, 15 insertions(+)
diff --git a/lib/x86/msr.h b/lib/x86/msr.h
index 29fff553..0e3fd037 100644
--- a/lib/x86/msr.h
+++ b/lib/x86/msr.h
@@ -36,6 +36,9 @@
#define MSR_IA32_PRED_CMD 0x00000049
#define PRED_CMD_IBPB BIT(0)
+#define MSR_IA32_FLUSH_CMD 0x0000010b
+#define L1D_FLUSH BIT(0)
+
#define MSR_IA32_PMC0 0x000004c1
#define MSR_IA32_PERFCTR0 0x000000c1
#define MSR_IA32_PERFCTR1 0x000000c2
diff --git a/lib/x86/processor.h b/lib/x86/processor.h
index aed6d180..e32c84f7 100644
--- a/lib/x86/processor.h
+++ b/lib/x86/processor.h
@@ -246,6 +246,7 @@ static inline bool is_intel(void)
#define X86_FEATURE_SHSTK (CPUID(0x7, 0, ECX, 7))
#define X86_FEATURE_IBT (CPUID(0x7, 0, EDX, 20))
#define X86_FEATURE_SPEC_CTRL (CPUID(0x7, 0, EDX, 26))
+#define X86_FEATURE_FLUSH_L1D (CPUID(0x7, 0, EDX, 28))
#define X86_FEATURE_ARCH_CAPABILITIES (CPUID(0x7, 0, EDX, 29))
#define X86_FEATURE_PKS (CPUID(0x7, 0, ECX, 31))
diff --git a/x86/msr.c b/x86/msr.c
index 13cb6391..f6be2be7 100644
--- a/x86/msr.c
+++ b/x86/msr.c
@@ -295,6 +295,17 @@ static void test_cmd_msrs(void)
}
for (i = 1; i < 64; i++)
test_wrmsr_fault(MSR_IA32_PRED_CMD, "PRED_CMD", BIT_ULL(i));
+
+ test_rdmsr_fault(MSR_IA32_FLUSH_CMD, "FLUSH_CMD");
+ if (this_cpu_has(X86_FEATURE_FLUSH_L1D)) {
+ test_wrmsr(MSR_IA32_FLUSH_CMD, "FLUSH_CMD", 0);
+ test_wrmsr(MSR_IA32_FLUSH_CMD, "FLUSH_CMD", L1D_FLUSH);
+ } else {
+ test_wrmsr_fault(MSR_IA32_FLUSH_CMD, "FLUSH_CMD", 0);
+ test_wrmsr_fault(MSR_IA32_FLUSH_CMD, "FLUSH_CMD", L1D_FLUSH);
+ }
+ for (i = 1; i < 64; i++)
+ test_wrmsr_fault(MSR_IA32_FLUSH_CMD, "FLUSH_CMD", BIT_ULL(i));
}
int main(int ac, char **av)
--
2.40.0.348.gf938b09366-goog
