[PATCH v3 15/23] arm64: KVM: VHE: Implement VHE activate/deactivate_traps

Marc Zyngier
2016-02-03T18:04:06Z

Running the kernel in HYP mode requires the HCR_E2H bit to be set
at all times, and the HCR_TGE bit to be set when running as a host
(and cleared when running as a guest). At the same time, the vector
must be set to the current role of the kernel (either host or
hypervisor), and a couple of system registers differ between VHE
and non-VHE.

We implement these by using another set of alternate functions
that get dynamically patched.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/include/asm/kvm_arm.h | 3 ++-
arch/arm64/include/asm/kvm_emulate.h | 3 +++
arch/arm64/kvm/hyp/switch.c | 47 +++++++++++++++++++++++++++++++++---
3 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 498335e..100cbec 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -23,6 +23,7 @@
#include <asm/types.h>

/* Hyp Configuration Register (HCR) bits */
+#define HCR_E2H (UL(1) << 34)
#define HCR_ID (UL(1) << 33)
#define HCR_CD (UL(1) << 32)
#define HCR_RW_SHIFT 31
@@ -81,7 +82,7 @@
HCR_AMO | HCR_SWIO | HCR_TIDCP | HCR_RW)
#define HCR_VIRT_EXCP_MASK (HCR_VA | HCR_VI | HCR_VF)
#define HCR_INT_OVERRIDE (HCR_FMO | HCR_IMO)
-
+#define HCR_HOST_VHE_FLAGS (HCR_RW | HCR_TGE | HCR_E2H)

/* Hyp System Control Register (SCTLR_EL2) bits */
#define SCTLR_EL2_EE (1 << 25)
diff --git a/arch/arm64/include/asm/kvm_emulate.h b/arch/arm64/include/asm/kvm_emulate.h
index 3066328..5ae0c69 100644
--- a/arch/arm64/include/asm/kvm_emulate.h
+++ b/arch/arm64/include/asm/kvm_emulate.h
@@ -29,6 +29,7 @@
#include <asm/kvm_mmio.h>
#include <asm/ptrace.h>
#include <asm/cputype.h>
+#include <asm/virt.h>

unsigned long *vcpu_reg32(const struct kvm_vcpu *vcpu, u8 reg_num);
unsigned long *vcpu_spsr32(const struct kvm_vcpu *vcpu);
@@ -43,6 +44,8 @@ void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu)
{
vcpu->arch.hcr_el2 = HCR_GUEST_FLAGS;
+ if (is_kernel_in_hyp_mode())
+ vcpu->arch.hcr_el2 |= HCR_E2H;
if (test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features))
vcpu->arch.hcr_el2 &= ~HCR_RW;
}
diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
index 0db161e..686ca35 100644
--- a/arch/arm64/kvm/hyp/switch.c
+++ b/arch/arm64/kvm/hyp/switch.c
@@ -15,6 +15,8 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/

+#include <asm/kvm_asm.h>
+
#include "hyp.h"

static bool __hyp_text __fpsimd_enabled_nvhe(void)
@@ -36,6 +38,27 @@ bool __hyp_text __fpsimd_enabled(void)
return __fpsimd_is_enabled()();
}

+static void __hyp_text __activate_traps_vhe(void)
+{
+ u64 val;
+
+ val = read_sysreg(cpacr_el1);
+ val |= CPACR_EL1_TTA;
+ val &= ~CPACR_EL1_FPEN;
+ write_sysreg(val, cpacr_el1);
+
+ write_sysreg(__kvm_hyp_vector, vbar_el1);
+}
+
+static void __hyp_text __activate_traps_nvhe(void)
+{
+ write_sysreg(CPTR_EL2_TTA | CPTR_EL2_TFP, cptr_el2);
+}
+
+static hyp_alternate_select(__activate_traps_arch,
+ __activate_traps_nvhe, __activate_traps_vhe,
+ ARM64_HAS_VIRT_HOST_EXTN);
+
static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
{
u64 val;
@@ -55,16 +78,34 @@ static void __hyp_text __activate_traps(struct kvm_vcpu *vcpu)
write_sysreg(val, hcr_el2);
/* Trap on AArch32 cp15 c15 accesses (EL1 or EL0) */
write_sysreg(1 << 15, hstr_el2);
- write_sysreg(CPTR_EL2_TTA | CPTR_EL2_TFP, cptr_el2);
write_sysreg(vcpu->arch.mdcr_el2, mdcr_el2);
+ __activate_traps_arch()();
}

-static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
+static void __hyp_text __deactivate_traps_vhe(void)
+{
+ extern char vectors[]; /* kernel exception vectors */
+
+ write_sysreg(HCR_HOST_VHE_FLAGS, hcr_el2);
+ write_sysreg(CPACR_EL1_FPEN, cpacr_el1);
+ write_sysreg(vectors, vbar_el1);
+}
+
+static void __hyp_text __deactivate_traps_nvhe(void)
{
write_sysreg(HCR_RW, hcr_el2);
+ write_sysreg(0, cptr_el2);
+}
+
+static hyp_alternate_select(__deactivate_traps_arch,
+ __deactivate_traps_nvhe, __deactivate_traps_vhe,
+ ARM64_HAS_VIRT_HOST_EXTN);
+
+static void __hyp_text __deactivate_traps(struct kvm_vcpu *vcpu)
+{
+ __deactivate_traps_arch()();
write_sysreg(0, hstr_el2);
write_sysreg(read_sysreg(mdcr_el2) & MDCR_EL2_HPMN_MASK, mdcr_el2);
- write_sysreg(0, cptr_el2);
}

static void __hyp_text __activate_vm(struct kvm_vcpu *vcpu)
--
2.1.4