MIPS: KVM: Add base guest MSA support
Add base code for supporting the MIPS SIMD Architecture (MSA) in MIPS
KVM guests. MSA cannot yet be enabled in the guest, we're just laying
the groundwork.
As with the FPU, whether the guest's MSA context is loaded is stored in
another bit in the fpu_inuse vcpu member. This allows MSA to be disabled
when the guest disables it, but keeping the MSA context loaded so it
doesn't have to be reloaded if the guest re-enables it.
New assembly code is added for saving and restoring the MSA context,
restoring only the upper half of the MSA context (for if the FPU context
is already loaded) and for saving/clearing and restoring MSACSR (which
can itself cause an MSA FP exception depending on the value). The MSACSR
is restored before returning to the guest if MSA is already enabled, and
the existing FP exception die notifier is extended to catch the possible
MSA FP exception and step over the ctcmsa instruction.
The helper function kvm_own_msa() is added to enable MSA and restore
the MSA context if it isn't already loaded, which will be used in a
later patch when the guest attempts to use MSA for the first time and
triggers an MSA disabled exception.
The existing FPU helpers are extended to handle MSA. kvm_lose_fpu()
saves the full MSA context if it is loaded (which includes the FPU
context) and both kvm_lose_fpu() and kvm_drop_fpu() disable MSA.
kvm_own_fpu() also needs to lose any MSA context if FR=0, since there
would be a risk of getting reserved instruction exceptions if CU1 is
enabled and we later try and save the MSA context. We shouldn't usually
hit this case since it will be handled when emulating CU1 changes,
however there's nothing to stop the guest modifying the Status register
directly via the comm page, which will cause this case to get hit.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: linux-mips@linux-mips.org
Cc: kvm@vger.kernel.org
diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index fb264d8..1dc0dca 100644
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -360,6 +360,7 @@
};
#define KVM_MIPS_FPU_FPU 0x1
+#define KVM_MIPS_FPU_MSA 0x2
#define KVM_MIPS_GUEST_TLB_SIZE 64
struct kvm_vcpu_arch {
@@ -432,6 +433,7 @@
int wait;
u8 fpu_enabled;
+ u8 msa_enabled;
};
@@ -576,6 +578,18 @@
kvm_read_c0_guest_config1(vcpu->cop0) & MIPS_CONF1_FP;
}
+static inline bool kvm_mips_guest_can_have_msa(struct kvm_vcpu_arch *vcpu)
+{
+ return (!__builtin_constant_p(cpu_has_msa) || cpu_has_msa) &&
+ vcpu->msa_enabled;
+}
+
+static inline bool kvm_mips_guest_has_msa(struct kvm_vcpu_arch *vcpu)
+{
+ return kvm_mips_guest_can_have_msa(vcpu) &&
+ kvm_read_c0_guest_config3(vcpu->cop0) & MIPS_CONF3_MSA;
+}
+
struct kvm_mips_callbacks {
int (*handle_cop_unusable)(struct kvm_vcpu *vcpu);
int (*handle_tlb_mod)(struct kvm_vcpu *vcpu);
@@ -619,11 +633,16 @@
/* Trampoline ASM routine to start running in "Guest" context */
extern int __kvm_mips_vcpu_run(struct kvm_run *run, struct kvm_vcpu *vcpu);
-/* FPU context management */
+/* FPU/MSA context management */
void __kvm_save_fpu(struct kvm_vcpu_arch *vcpu);
void __kvm_restore_fpu(struct kvm_vcpu_arch *vcpu);
void __kvm_restore_fcsr(struct kvm_vcpu_arch *vcpu);
+void __kvm_save_msa(struct kvm_vcpu_arch *vcpu);
+void __kvm_restore_msa(struct kvm_vcpu_arch *vcpu);
+void __kvm_restore_msa_upper(struct kvm_vcpu_arch *vcpu);
+void __kvm_restore_msacsr(struct kvm_vcpu_arch *vcpu);
void kvm_own_fpu(struct kvm_vcpu *vcpu);
+void kvm_own_msa(struct kvm_vcpu *vcpu);
void kvm_drop_fpu(struct kvm_vcpu *vcpu);
void kvm_lose_fpu(struct kvm_vcpu *vcpu);