| Message ID | 20241004152804.72508-20-steven.price@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: Support for Arm CCA in KVM | expand |
Steven Price <steven.price@arm.com> 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@arm.com> > --- > 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
On 07/10/2024 05:31, Aneesh Kumar K.V wrote: > Steven Price <steven.price@arm.com> 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@arm.com> >> --- >> 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 The PC is ignored when restarting realm guest, so kvm_incr_pr() is effectively a no-op. But I guess REC_ENTER_EMULATED_MMIO is our way of signalling to the RMM that it should skip the instruction, so your proposed patch below makes the code slightly clearer. Thanks, Steve > 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
On 04/10/2024 16:27, Steven Price wrote: > 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@arm.com> > --- > 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; Should we additionally handle injecting an abort if there was no valid syndrome information ? Like we do for protected VMs and normal VMs when userspace doesn't offer to help ? > > @@ -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; I wonder if we can skip this here and we can sync the "enter.gprs[]" from vcpu state at rec_enter, similar to what we do for PSCI/HOST call exits. Also the ESR_ELx_SRT is always x0 for a Realm exit. So, we should always find the enter.gpr[0] in vcpu.regs[0] at rec_enter. Suzuki > + else > + vcpu_set_reg(vcpu, kvm_vcpu_dabt_get_rd(vcpu), data); > } > > /* > 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); > } >
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); } /* 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); }
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@arm.com> --- 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(-)