Steven Price <steven.price@xxxxxxx> writes:
> MMIO emulation for a realm cannot be done directly with the VM's
> registers as they are protected from the host. However, for emulatable
> data aborts, the RMM uses GPRS[0] to provide the read/written value.
> We can transfer this from/to the equivalent VCPU's register entry and
> then depend on the generic MMIO handling code in KVM.
>
> For a MMIO read, the value is placed in the shared RecExit structure
> during kvm_handle_mmio_return() rather than in the VCPU's register
> entry.
>
> Signed-off-by: Steven Price <steven.price@xxxxxxx>
> ---
> v3: Adapt to previous patch changes
> ---
> arch/arm64/kvm/mmio.c | 10 +++++++++-
> arch/arm64/kvm/rme-exit.c | 6 ++++++
> 2 files changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c
> index cd6b7b83e2c3..66a838b3776a 100644
> --- a/arch/arm64/kvm/mmio.c
> +++ b/arch/arm64/kvm/mmio.c
> @@ -6,6 +6,7 @@
>
> #include <linux/kvm_host.h>
> #include <asm/kvm_emulate.h>
> +#include <asm/rmi_smc.h>
> #include <trace/events/kvm.h>
>
> #include "trace.h"
> @@ -90,6 +91,9 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
>
> vcpu->mmio_needed = 0;
>
> + if (vcpu_is_rec(vcpu))
> + vcpu->arch.rec.run->enter.flags |= REC_ENTER_EMULATED_MMIO;
> +
> if (!kvm_vcpu_dabt_iswrite(vcpu)) {
> struct kvm_run *run = vcpu->run;
>
> @@ -108,7 +112,11 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
> trace_kvm_mmio(KVM_TRACE_MMIO_READ, len, run->mmio.phys_addr,
> &data);
> data = vcpu_data_host_to_guest(vcpu, data, len);
> - vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data);
> +
> + if (vcpu_is_rec(vcpu))
> + vcpu->arch.rec.run->enter.gprs[0] = data;
> + else
> + vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data);
> }
>
> /*
>
Does a kvm_incr_pc(vcpu); make sense for realm guest? Should we do
modified arch/arm64/kvm/mmio.c
@@ -91,9 +91,6 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
vcpu->mmio_needed = 0;
- if (vcpu_is_rec(vcpu))
- vcpu->arch.rec.run->enter.flags |= RMI_EMULATED_MMIO;
-
if (!kvm_vcpu_dabt_iswrite(vcpu)) {
struct kvm_run *run = vcpu->run;
@@ -123,7 +120,10 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
* The MMIO instruction is emulated and should not be re-executed
* in the guest.
*/
- kvm_incr_pc(vcpu);
+ if (vcpu_is_rec(vcpu))
+ vcpu->arch.rec.run->enter.flags |= RMI_EMULATED_MMIO;
+ else
+ kvm_incr_pc(vcpu);
return 1;
}
> diff --git a/arch/arm64/kvm/rme-exit.c b/arch/arm64/kvm/rme-exit.c
> index e96ea308212c..1ddbff123149 100644
> --- a/arch/arm64/kvm/rme-exit.c
> +++ b/arch/arm64/kvm/rme-exit.c
> @@ -25,6 +25,12 @@ static int rec_exit_reason_notimpl(struct kvm_vcpu *vcpu)
>
> static int rec_exit_sync_dabt(struct kvm_vcpu *vcpu)
> {
> + struct realm_rec *rec = &vcpu->arch.rec;
> +
> + if (kvm_vcpu_dabt_iswrite(vcpu) && kvm_vcpu_dabt_isvalid(vcpu))
> + vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu),
> + rec->run->exit.gprs[0]);
> +
> return kvm_handle_guest_abort(vcpu);
> }
>
> --
> 2.34.1
