arm64: KVM: Add ARCH_WORKAROUND_2 support for guests

In order to offer ARCH_WORKAROUND_2 support to guests, we need
a bit of infrastructure.

Let's add a flag indicating whether or not the guest uses
SSBD mitigation. Depending on the state of this flag, allow
KVM to disable ARCH_WORKAROUND_2 before entering the guest,
and enable it when exiting it.

Reviewed-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marc Zyngier 2018-05-29 13:11:16 +01:00 committed by Catalin Marinas
parent 85478bab40
commit 55e3748e89
6 changed files with 81 additions and 0 deletions

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@ -319,6 +319,11 @@ static inline int kvm_map_vectors(void)
return 0;
}
static inline int hyp_map_aux_data(void)
{
return 0;
}
#define kvm_phys_to_vttbr(addr) (addr)
#endif /* !__ASSEMBLY__ */

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@ -33,6 +33,9 @@
#define KVM_ARM64_DEBUG_DIRTY_SHIFT 0
#define KVM_ARM64_DEBUG_DIRTY (1 << KVM_ARM64_DEBUG_DIRTY_SHIFT)
#define VCPU_WORKAROUND_2_FLAG_SHIFT 0
#define VCPU_WORKAROUND_2_FLAG (_AC(1, UL) << VCPU_WORKAROUND_2_FLAG_SHIFT)
/* Translate a kernel address of @sym into its equivalent linear mapping */
#define kvm_ksym_ref(sym) \
({ \

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@ -216,6 +216,9 @@ struct kvm_vcpu_arch {
/* Exception Information */
struct kvm_vcpu_fault_info fault;
/* State of various workarounds, see kvm_asm.h for bit assignment */
u64 workaround_flags;
/* Guest debug state */
u64 debug_flags;

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@ -456,6 +456,30 @@ static inline int kvm_map_vectors(void)
}
#endif
#ifdef CONFIG_ARM64_SSBD
DECLARE_PER_CPU_READ_MOSTLY(u64, arm64_ssbd_callback_required);
static inline int hyp_map_aux_data(void)
{
int cpu, err;
for_each_possible_cpu(cpu) {
u64 *ptr;
ptr = per_cpu_ptr(&arm64_ssbd_callback_required, cpu);
err = create_hyp_mappings(ptr, ptr + 1, PAGE_HYP);
if (err)
return err;
}
return 0;
}
#else
static inline int hyp_map_aux_data(void)
{
return 0;
}
#endif
#define kvm_phys_to_vttbr(addr) phys_to_ttbr(addr)
#endif /* __ASSEMBLY__ */

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@ -15,6 +15,7 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/arm-smccc.h>
#include <linux/types.h>
#include <linux/jump_label.h>
#include <uapi/linux/psci.h>
@ -389,6 +390,39 @@ static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
return false;
}
static inline bool __hyp_text __needs_ssbd_off(struct kvm_vcpu *vcpu)
{
if (!cpus_have_const_cap(ARM64_SSBD))
return false;
return !(vcpu->arch.workaround_flags & VCPU_WORKAROUND_2_FLAG);
}
static void __hyp_text __set_guest_arch_workaround_state(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_ARM64_SSBD
/*
* The host runs with the workaround always present. If the
* guest wants it disabled, so be it...
*/
if (__needs_ssbd_off(vcpu) &&
__hyp_this_cpu_read(arm64_ssbd_callback_required))
arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 0, NULL);
#endif
}
static void __hyp_text __set_host_arch_workaround_state(struct kvm_vcpu *vcpu)
{
#ifdef CONFIG_ARM64_SSBD
/*
* If the guest has disabled the workaround, bring it back on.
*/
if (__needs_ssbd_off(vcpu) &&
__hyp_this_cpu_read(arm64_ssbd_callback_required))
arm_smccc_1_1_smc(ARM_SMCCC_ARCH_WORKAROUND_2, 1, NULL);
#endif
}
/* Switch to the guest for VHE systems running in EL2 */
int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
{
@ -409,6 +443,8 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
sysreg_restore_guest_state_vhe(guest_ctxt);
__debug_switch_to_guest(vcpu);
__set_guest_arch_workaround_state(vcpu);
do {
/* Jump in the fire! */
exit_code = __guest_enter(vcpu, host_ctxt);
@ -416,6 +452,8 @@ int kvm_vcpu_run_vhe(struct kvm_vcpu *vcpu)
/* And we're baaack! */
} while (fixup_guest_exit(vcpu, &exit_code));
__set_host_arch_workaround_state(vcpu);
fp_enabled = fpsimd_enabled_vhe();
sysreg_save_guest_state_vhe(guest_ctxt);
@ -465,6 +503,8 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu)
__sysreg_restore_state_nvhe(guest_ctxt);
__debug_switch_to_guest(vcpu);
__set_guest_arch_workaround_state(vcpu);
do {
/* Jump in the fire! */
exit_code = __guest_enter(vcpu, host_ctxt);
@ -472,6 +512,8 @@ int __hyp_text __kvm_vcpu_run_nvhe(struct kvm_vcpu *vcpu)
/* And we're baaack! */
} while (fixup_guest_exit(vcpu, &exit_code));
__set_host_arch_workaround_state(vcpu);
fp_enabled = __fpsimd_enabled_nvhe();
__sysreg_save_state_nvhe(guest_ctxt);

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@ -1490,6 +1490,10 @@ static int init_hyp_mode(void)
}
}
err = hyp_map_aux_data();
if (err)
kvm_err("Cannot map host auxilary data: %d\n", err);
return 0;
out_err: