On 01/02/16 14:20, Christoffer Dall wrote:
> On Mon, Jan 25, 2016 at 03:53:48PM +0000, Marc Zyngier wrote:
>> 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@xxxxxxx>
>> ---
>> arch/arm64/include/asm/kvm_arm.h | 1 +
>> arch/arm64/include/asm/kvm_emulate.h | 3 +++
>> arch/arm64/kvm/hyp/switch.c | 52 +++++++++++++++++++++++++++++++++---
>> 3 files changed, 53 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
>> index 738a95f..73d3826 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
>> 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 6f264dc..77f7c94 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 |= 1 << 28;
>> + val &= ~(3 << 20);
>
> could you define these bitfields as well?
Sure.
>
>> + 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 +78,39 @@ 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 */
>> + u64 val;
>> +
>> + write_sysreg(HCR_RW | HCR_TGE | HCR_E2H, hcr_el2);
>
> perhaps we should define the EL2_HOST_HCR bit settings somewhere
> globally and reuse that here?
I'm going for HCR_HOST_VHE_FLAGS, as a pendant to HCR_GUEST_FLAGS.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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