Cache whether or not forced emulation is availability during setup_idt()
so that tests can force emulation (or not) in contexts where taking an
exception of any kind will fail.
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
lib/x86/desc.c | 22 ++++++++++++++++++++++
lib/x86/desc.h | 14 +-------------
x86/access.c | 2 +-
x86/emulator.c | 11 +++++------
x86/emulator64.c | 2 +-
x86/la57.c | 2 +-
x86/lam.c | 2 +-
x86/msr.c | 2 +-
x86/pmu.c | 2 +-
9 files changed, 34 insertions(+), 25 deletions(-)
diff --git a/lib/x86/desc.c b/lib/x86/desc.c
index 5748f900..fca37b9a 100644
--- a/lib/x86/desc.c
+++ b/lib/x86/desc.c
@@ -298,6 +298,22 @@ static void *idt_handlers[32] = {
[21] = &cp_fault,
};
+bool is_fep_available;
+
+static bool __is_fep_available(void)
+{
+ /*
+ * Use the non-FEP ASM_TRY() as KVM will inject a #UD on the prefix
+ * itself if forced emulation is not available.
+ */
+ asm goto(ASM_TRY("%l[fep_unavailable]")
+ KVM_FEP "nop\n\t"
+ ::: "memory" : fep_unavailable);
+ return true;
+fep_unavailable:
+ return false;
+}
+
void setup_idt(void)
{
int i;
@@ -311,6 +327,12 @@ void setup_idt(void)
}
load_idt();
+
+ /*
+ * Detect support for forced emulation *after* loading the IDT, as this
+ * will #UD if FEP is unavailable.
+ */
+ is_fep_available = __is_fep_available();
}
void load_idt(void)
diff --git a/lib/x86/desc.h b/lib/x86/desc.h
index a1e60e78..68f38f3d 100644
--- a/lib/x86/desc.h
+++ b/lib/x86/desc.h
@@ -164,19 +164,7 @@ typedef struct __attribute__((packed)) {
#define KVM_FEP "ud2; .byte 'k', 'v', 'm';"
#define ASM_TRY_FEP(catch) __ASM_TRY(KVM_FEP, catch)
-static inline bool is_fep_available(void)
-{
- /*
- * Use the non-FEP ASM_TRY() as KVM will inject a #UD on the prefix
- * itself if forced emulation is not available.
- */
- asm goto(ASM_TRY("%l[fep_unavailable]")
- KVM_FEP "nop\n\t"
- ::: "memory" : fep_unavailable);
- return true;
-fep_unavailable:
- return false;
-}
+extern bool is_fep_available;
typedef struct {
unsigned short offset0;
diff --git a/x86/access.c b/x86/access.c
index f90a72d6..d94910bf 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -1232,7 +1232,7 @@ void ac_test_run(int pt_levels, bool force_emulation)
ac_pt_env_t pt_env;
int i, tests, successes;
- if (force_emulation && !is_fep_available()) {
+ if (force_emulation && !is_fep_available) {
report_skip("Forced emulation prefix (FEP) not available\n");
return;
}
diff --git a/x86/emulator.c b/x86/emulator.c
index f8bdc26b..4e1ba12a 100644
--- a/x86/emulator.c
+++ b/x86/emulator.c
@@ -728,7 +728,6 @@ static void handle_db(struct ex_regs *regs)
static void test_mov_pop_ss_code_db(void)
{
handler old_db_handler = handle_exception(DB_VECTOR, handle_db);
- bool fep_available = is_fep_available();
/* On Intel, code #DBs are inhibited when MOV/POP SS blocking is active. */
int nr_expected = is_intel() ? 0 : 1;
@@ -761,7 +760,7 @@ static void test_mov_pop_ss_code_db(void)
"mov %%ss, %0\n\t", "mov %0, %%ss\n\t")
MOV_SS_DB("no fep", "", "");
- if (fep_available) {
+ if (is_fep_available) {
MOV_SS_DB("fep MOV-SS", KVM_FEP, "");
MOV_SS_DB("fep XOR", "", KVM_FEP);
MOV_SS_DB("fep MOV-SS/fep XOR", KVM_FEP, KVM_FEP);
@@ -774,7 +773,7 @@ static void test_mov_pop_ss_code_db(void)
"push %%ss\n\t", "pop %%ss\n\t")
POP_SS_DB("no fep", "", "");
- if (fep_available) {
+ if (is_fep_available) {
POP_SS_DB("fep POP-SS", KVM_FEP, "");
POP_SS_DB("fep XOR", "", KVM_FEP);
POP_SS_DB("fep POP-SS/fep XOR", KVM_FEP, KVM_FEP);
@@ -791,8 +790,8 @@ int main(void)
void *mem;
void *cross_mem;
- if (!is_fep_available())
- report_skip("Skipping tests the require forced emulation, "
+ if (!is_fep_available)
+ report_skip("Skipping tests that require forced emulation, "
"use kvm.force_emulation_prefix=1 to enable");
setup_vm();
@@ -821,7 +820,7 @@ int main(void)
//test_lldt(mem);
test_ltr(mem);
- if (is_fep_available()) {
+ if (is_fep_available) {
test_smsw_reg(mem);
test_nop(mem);
test_mov_dr(mem);
diff --git a/x86/emulator64.c b/x86/emulator64.c
index 5d1bb0f0..138903af 100644
--- a/x86/emulator64.c
+++ b/x86/emulator64.c
@@ -478,7 +478,7 @@ static void test_emulator_64(void *mem)
test_sreg(mem);
test_cmov(mem);
- if (is_fep_available()) {
+ if (is_fep_available) {
test_mmx_movq_mf(mem);
test_movabs(mem);
test_user_load_dpl0_seg();
diff --git a/x86/la57.c b/x86/la57.c
index 41764110..d93e286c 100644
--- a/x86/la57.c
+++ b/x86/la57.c
@@ -313,7 +313,7 @@ static void test_canonical_checks(void)
{
__test_canonical_checks(false);
- if (is_fep_available())
+ if (is_fep_available)
__test_canonical_checks(true);
else
report_skip("Force emulation prefix not enabled");
diff --git a/x86/lam.c b/x86/lam.c
index a1c98949..8ad68178 100644
--- a/x86/lam.c
+++ b/x86/lam.c
@@ -184,7 +184,7 @@ static void __test_lam_sup(void *vaddr, void *vaddr_mmio)
test_ptr(vaddr_mmio, true);
test_invpcid(vaddr);
test_invlpg(vaddr, false);
- if (is_fep_available())
+ if (is_fep_available)
test_invlpg(vaddr, true);
}
diff --git a/x86/msr.c b/x86/msr.c
index e21ff0ac..f582a584 100644
--- a/x86/msr.c
+++ b/x86/msr.c
@@ -313,7 +313,7 @@ static void test_cmd_msrs(void)
test_wrmsr_fault(MSR_IA32_FLUSH_CMD, "FLUSH_CMD", L1D_FLUSH);
}
- if (is_fep_available()) {
+ if (is_fep_available) {
for (i = 1; i < 64; i++)
test_wrmsr_fep_fault(MSR_IA32_FLUSH_CMD, "FLUSH_CMD", BIT_ULL(i));
}
diff --git a/x86/pmu.c b/x86/pmu.c
index 8cf26b12..b794b7d8 100644
--- a/x86/pmu.c
+++ b/x86/pmu.c
@@ -823,7 +823,7 @@ static void warm_up(void)
static void check_counters(void)
{
- if (is_fep_available())
+ if (is_fep_available)
check_emulated_instr();
warm_up();
--
2.49.0.1266.g31b7d2e469-goog
