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| author | Marc Zyngier <maz@kernel.org> | 2023-04-05 13:48:58 +0200 |
|---|---|---|
| committer | Marc Zyngier <maz@kernel.org> | 2023-04-05 20:20:23 +0200 |
| commit | 0e5c9a9d6548e9b178d4696c696ae4a21c39ae58 (patch) | |
| tree | edaae95c99c0540db8de44a759e8f5242be57e68 | |
| parent | KVM: selftests: Add test for SMCCC filter (diff) | |
| download | linux-0e5c9a9d6548e9b178d4696c696ae4a21c39ae58.tar.xz linux-0e5c9a9d6548e9b178d4696c696ae4a21c39ae58.zip | |
KVM: arm64: Expose SMC/HVC width to userspace
When returning to userspace to handle a SMCCC call, we consistently
set PC to point to the instruction immediately after the HVC/SMC.
However, should userspace need to know the exact address of the
trapping instruction, it needs to know about the *size* of that
instruction. For AArch64, this is pretty easy. For AArch32, this
is a bit more funky, as Thumb has 16bit encodings for both HVC
and SMC.
Expose this to userspace with a new flag that directly derives
from ESR_EL2.IL. Also update the documentation to reflect the PC
state at the point of exit.
Finally, this fixes a small buglet where the hypercall.{args,ret}
fields would not be cleared on exit, and could contain some
random junk.
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/86pm8iv8tj.wl-maz@kernel.org
| -rw-r--r-- | Documentation/virt/kvm/api.rst | 8 | ||||
| -rw-r--r-- | arch/arm64/include/uapi/asm/kvm.h | 3 | ||||
| -rw-r--r-- | arch/arm64/kvm/hypercalls.c | 16 |
3 files changed, 21 insertions, 6 deletions
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index c8ab2f730945..103f945959ed 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -6244,6 +6244,14 @@ Definition of ``flags``: conduit to initiate the SMCCC call. If this bit is 0 then the guest used the HVC conduit for the SMCCC call. + - ``KVM_HYPERCALL_EXIT_16BIT``: Indicates that the guest used a 16bit + instruction to initiate the SMCCC call. If this bit is 0 then the + guest used a 32bit instruction. An AArch64 guest always has this + bit set to 0. + +At the point of exit, PC points to the instruction immediately following +the trapping instruction. + :: /* KVM_EXIT_TPR_ACCESS */ diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h index 3dcfa4bfdf83..b1c1edf85480 100644 --- a/arch/arm64/include/uapi/asm/kvm.h +++ b/arch/arm64/include/uapi/asm/kvm.h @@ -491,7 +491,8 @@ struct kvm_smccc_filter { }; /* arm64-specific KVM_EXIT_HYPERCALL flags */ -#define KVM_HYPERCALL_EXIT_SMC (1U << 0) +#define KVM_HYPERCALL_EXIT_SMC (1U << 0) +#define KVM_HYPERCALL_EXIT_16BIT (1U << 1) #endif diff --git a/arch/arm64/kvm/hypercalls.c b/arch/arm64/kvm/hypercalls.c index 9a35d6d18193..3b6523f25afc 100644 --- a/arch/arm64/kvm/hypercalls.c +++ b/arch/arm64/kvm/hypercalls.c @@ -222,13 +222,19 @@ static void kvm_prepare_hypercall_exit(struct kvm_vcpu *vcpu, u32 func_id) { u8 ec = ESR_ELx_EC(kvm_vcpu_get_esr(vcpu)); struct kvm_run *run = vcpu->run; - - run->exit_reason = KVM_EXIT_HYPERCALL; - run->hypercall.nr = func_id; - run->hypercall.flags = 0; + u64 flags = 0; if (ec == ESR_ELx_EC_SMC32 || ec == ESR_ELx_EC_SMC64) - run->hypercall.flags |= KVM_HYPERCALL_EXIT_SMC; + flags |= KVM_HYPERCALL_EXIT_SMC; + + if (!kvm_vcpu_trap_il_is32bit(vcpu)) + flags |= KVM_HYPERCALL_EXIT_16BIT; + + run->exit_reason = KVM_EXIT_HYPERCALL; + run->hypercall = (typeof(run->hypercall)) { + .nr = func_id, + .flags = flags, + }; } int kvm_smccc_call_handler(struct kvm_vcpu *vcpu) |