Loongson Binary Translation (LBT) is used to accelerate binary translation,
which contains 4 scratch registers (scr0 to scr3), x86/ARM eflags (eflags)
and x87 fpu stack pointer (ftop).
Like FPU extension, here late enabling method is used for LBT. LBT context
is saved/restored on vcpu context switch path.
Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
---
arch/loongarch/include/asm/kvm_host.h | 8 ++++
arch/loongarch/include/asm/kvm_vcpu.h | 6 +++
arch/loongarch/kvm/exit.c | 9 ++++
arch/loongarch/kvm/vcpu.c | 66 ++++++++++++++++++++++++++-
4 files changed, 88 insertions(+), 1 deletion(-)
diff --git a/arch/loongarch/include/asm/kvm_host.h b/arch/loongarch/include/asm/kvm_host.h
index 44b54965f5b4..c409ab15bae1 100644
--- a/arch/loongarch/include/asm/kvm_host.h
+++ b/arch/loongarch/include/asm/kvm_host.h
@@ -137,6 +137,7 @@ enum emulation_result {
#define KVM_LARCH_LASX (0x1 << 2)
#define KVM_LARCH_SWCSR_LATEST (0x1 << 3)
#define KVM_LARCH_HWCSR_USABLE (0x1 << 4)
+#define KVM_LARCH_LBT (0x1 << 5)
struct kvm_vcpu_arch {
/*
@@ -170,6 +171,7 @@ struct kvm_vcpu_arch {
/* FPU state */
struct loongarch_fpu fpu FPU_ALIGN;
+ struct loongarch_lbt lbt;
/* CSR state */
struct loongarch_csrs *csr;
@@ -241,6 +243,12 @@ static inline bool kvm_guest_has_lasx(struct kvm_vcpu_arch *arch)
return arch->cpucfg[2] & CPUCFG2_LASX;
}
+static inline bool kvm_guest_has_lbt(struct kvm_vcpu_arch *arch)
+{
+ return arch->cpucfg[2] & (CPUCFG2_X86BT | CPUCFG2_ARMBT
+ | CPUCFG2_MIPSBT);
+}
+
/* Debug: dump vcpu state */
int kvm_arch_vcpu_dump_regs(struct kvm_vcpu *vcpu);
diff --git a/arch/loongarch/include/asm/kvm_vcpu.h b/arch/loongarch/include/asm/kvm_vcpu.h
index c416cb7125c0..3cc906a0ff54 100644
--- a/arch/loongarch/include/asm/kvm_vcpu.h
+++ b/arch/loongarch/include/asm/kvm_vcpu.h
@@ -75,6 +75,12 @@ static inline void kvm_save_lasx(struct loongarch_fpu *fpu) { }
static inline void kvm_restore_lasx(struct loongarch_fpu *fpu) { }
#endif
+#ifdef CONFIG_CPU_HAS_LBT
+int kvm_own_lbt(struct kvm_vcpu *vcpu);
+#else
+static inline int kvm_own_lbt(struct kvm_vcpu *vcpu) { return -EINVAL; }
+#endif
+
void kvm_init_timer(struct kvm_vcpu *vcpu, unsigned long hz);
void kvm_reset_timer(struct kvm_vcpu *vcpu);
void kvm_save_timer(struct kvm_vcpu *vcpu);
diff --git a/arch/loongarch/kvm/exit.c b/arch/loongarch/kvm/exit.c
index ea73f9dc2cc6..be2c326253a3 100644
--- a/arch/loongarch/kvm/exit.c
+++ b/arch/loongarch/kvm/exit.c
@@ -835,6 +835,14 @@ static int kvm_handle_hypercall(struct kvm_vcpu *vcpu)
return ret;
}
+static int kvm_handle_lbt_disabled(struct kvm_vcpu *vcpu)
+{
+ if (kvm_own_lbt(vcpu))
+ kvm_queue_exception(vcpu, EXCCODE_INE, 0);
+
+ return RESUME_GUEST;
+}
+
/*
* LoongArch KVM callback handling for unimplemented guest exiting
*/
@@ -867,6 +875,7 @@ static exit_handle_fn kvm_fault_tables[EXCCODE_INT_START] = {
[EXCCODE_LASXDIS] = kvm_handle_lasx_disabled,
[EXCCODE_GSPR] = kvm_handle_gspr,
[EXCCODE_HVC] = kvm_handle_hypercall,
+ [EXCCODE_BTDIS] = kvm_handle_lbt_disabled,
};
int kvm_handle_fault(struct kvm_vcpu *vcpu, int fault)
diff --git a/arch/loongarch/kvm/vcpu.c b/arch/loongarch/kvm/vcpu.c
index 16756ffb55e8..36db2b257a95 100644
--- a/arch/loongarch/kvm/vcpu.c
+++ b/arch/loongarch/kvm/vcpu.c
@@ -6,6 +6,7 @@
#include <linux/kvm_host.h>
#include <linux/entry-kvm.h>
#include <asm/fpu.h>
+#include <asm/lbt.h>
#include <asm/loongarch.h>
#include <asm/setup.h>
#include <asm/time.h>
@@ -977,12 +978,71 @@ int kvm_arch_vcpu_ioctl_set_fpu(struct kvm_vcpu *vcpu, struct kvm_fpu *fpu)
return 0;
}
+#ifdef CONFIG_CPU_HAS_LBT
+int kvm_own_lbt(struct kvm_vcpu *vcpu)
+{
+ if (!kvm_guest_has_lbt(&vcpu->arch))
+ return -EINVAL;
+
+ preempt_disable();
+ set_csr_euen(CSR_EUEN_LBTEN);
+
+ _restore_lbt(&vcpu->arch.lbt);
+ vcpu->arch.aux_inuse |= KVM_LARCH_LBT;
+ preempt_enable();
+ return 0;
+}
+
+static void kvm_lose_lbt(struct kvm_vcpu *vcpu)
+{
+ preempt_disable();
+ if (vcpu->arch.aux_inuse & KVM_LARCH_LBT) {
+ _save_lbt(&vcpu->arch.lbt);
+ clear_csr_euen(CSR_EUEN_LBTEN);
+ vcpu->arch.aux_inuse &= ~KVM_LARCH_LBT;
+ }
+ preempt_enable();
+}
+
+static void kvm_check_fscr(struct kvm_vcpu *vcpu, unsigned long fcsr)
+{
+ /*
+ * If TM is enabled, top register save/restore will
+ * cause lbt exception, here enable lbt in advance
+ */
+ if (fcsr & FPU_CSR_TM)
+ kvm_own_lbt(vcpu);
+}
+
+static void kvm_check_fcsr_alive(struct kvm_vcpu *vcpu)
+{
+ unsigned long fcsr;
+
+ if (vcpu->arch.aux_inuse & KVM_LARCH_FPU) {
+ if (vcpu->arch.aux_inuse & KVM_LARCH_LBT)
+ return;
+
+ fcsr = read_fcsr(LOONGARCH_FCSR0);
+ kvm_check_fscr(vcpu, fcsr);
+ }
+}
+#else
+static inline void kvm_lose_lbt(struct kvm_vcpu *vcpu) { }
+static inline void kvm_check_fscr(struct kvm_vcpu *vcpu,
+ unsigned long fcsr) { }
+static inline void kvm_check_fcsr_alive(struct kvm_vcpu *vcpu) { }
+#endif
+
/* Enable FPU and restore context */
void kvm_own_fpu(struct kvm_vcpu *vcpu)
{
preempt_disable();
- /* Enable FPU */
+ /*
+ * Enable FPU for guest
+ * Set FR and FRE according to guest context
+ */
+ kvm_check_fscr(vcpu, vcpu->arch.fpu.fcsr);
set_csr_euen(CSR_EUEN_FPEN);
kvm_restore_fpu(&vcpu->arch.fpu);
@@ -1002,6 +1062,7 @@ int kvm_own_lsx(struct kvm_vcpu *vcpu)
preempt_disable();
/* Enable LSX for guest */
+ kvm_check_fscr(vcpu, vcpu->arch.fpu.fcsr);
set_csr_euen(CSR_EUEN_LSXEN | CSR_EUEN_FPEN);
switch (vcpu->arch.aux_inuse & KVM_LARCH_FPU) {
case KVM_LARCH_FPU:
@@ -1036,6 +1097,7 @@ int kvm_own_lasx(struct kvm_vcpu *vcpu)
preempt_disable();
+ kvm_check_fscr(vcpu, vcpu->arch.fpu.fcsr);
set_csr_euen(CSR_EUEN_FPEN | CSR_EUEN_LSXEN | CSR_EUEN_LASXEN);
switch (vcpu->arch.aux_inuse & (KVM_LARCH_FPU | KVM_LARCH_LSX)) {
case KVM_LARCH_LSX:
@@ -1067,6 +1129,7 @@ void kvm_lose_fpu(struct kvm_vcpu *vcpu)
{
preempt_disable();
+ kvm_check_fcsr_alive(vcpu);
if (vcpu->arch.aux_inuse & KVM_LARCH_LASX) {
kvm_save_lasx(&vcpu->arch.fpu);
vcpu->arch.aux_inuse &= ~(KVM_LARCH_LSX | KVM_LARCH_FPU | KVM_LARCH_LASX);
@@ -1089,6 +1152,7 @@ void kvm_lose_fpu(struct kvm_vcpu *vcpu)
/* Disable FPU */
clear_csr_euen(CSR_EUEN_FPEN);
}
+ kvm_lose_lbt(vcpu);
preempt_enable();
}
--
2.39.3
