| Message ID | 20250213161426.102987-20-steven.price@arm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | arm64: Support for Arm CCA in KVM | expand |
On 2/14/25 2:13 AM, 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> > --- > Changes since v5: > * Inject SEA to the guest is an emulatable MMIO access triggers a data > abort. > * kvm_handle_mmio_return() - disable kvm_incr_pc() for a REC (as the PC > isn't under the host's control) and move the REC_ENTER_EMULATED_MMIO > flag setting to this location (as that tells the RMM to skip the > instruction). > --- > arch/arm64/kvm/inject_fault.c | 4 +++- > arch/arm64/kvm/mmio.c | 16 ++++++++++++---- > arch/arm64/kvm/rme-exit.c | 6 ++++++ > 3 files changed, 21 insertions(+), 5 deletions(-) > One nitpick below, with it addressed: Reviewed-by: Gavin Shan <gshan@redhat.com> > diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c > index a640e839848e..2a9682b9834f 100644 > --- a/arch/arm64/kvm/inject_fault.c > +++ b/arch/arm64/kvm/inject_fault.c > @@ -165,7 +165,9 @@ static void inject_abt32(struct kvm_vcpu *vcpu, bool is_pabt, u32 addr) > */ > void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr) > { > - if (vcpu_el1_is_32bit(vcpu)) > + if (unlikely(vcpu_is_rec(vcpu))) > + vcpu->arch.rec.run->enter.flags |= REC_ENTER_FLAG_INJECT_SEA; > + else if (vcpu_el1_is_32bit(vcpu)) > inject_abt32(vcpu, false, addr); > else > inject_abt64(vcpu, false, addr); > diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c > index ab365e839874..bff89d47a4d5 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" > @@ -136,14 +137,21 @@ 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); > } > > /* > * 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 |= REC_ENTER_FLAG_EMULATED_MMIO; > + else > + kvm_incr_pc(vcpu); > > return 1; > } > @@ -162,14 +170,14 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa) > * No valid syndrome? Ask userspace for help if it has > * volunteered to do so, and bail out otherwise. > * > - * In the protected VM case, there isn't much userspace can do > + * In the protected/realm VM case, there isn't much userspace can do > * though, so directly deliver an exception to the guest. > */ > if (!kvm_vcpu_dabt_isvalid(vcpu)) { > trace_kvm_mmio_nisv(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu), > kvm_vcpu_get_hfar(vcpu), fault_ipa); > > - if (vcpu_is_protected(vcpu)) { > + if (vcpu_is_protected(vcpu) || vcpu_is_rec(vcpu)) { > kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu)); > return 1; > } > diff --git a/arch/arm64/kvm/rme-exit.c b/arch/arm64/kvm/rme-exit.c > index aae1adefe1a3..c785005f821f 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]); > + A comment may be needed to explain why GPR[0] has to be copied over. The contexnt in GPR[0] isn't needed by all cases, being handled by kvm_handle_guest_abort(). Something like below. /* * Copy over GPR[0] to the target GPR, preparing to handle MMIO write * fault. The content to be written has been saved to GPR[0] by RMM. * It's overhead to other cases like fault due to MMIO read, shared * or private space access. */ > return kvm_handle_guest_abort(vcpu); > } > Thanks, Gavin
diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c index a640e839848e..2a9682b9834f 100644 --- a/arch/arm64/kvm/inject_fault.c +++ b/arch/arm64/kvm/inject_fault.c @@ -165,7 +165,9 @@ static void inject_abt32(struct kvm_vcpu *vcpu, bool is_pabt, u32 addr) */ void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr) { - if (vcpu_el1_is_32bit(vcpu)) + if (unlikely(vcpu_is_rec(vcpu))) + vcpu->arch.rec.run->enter.flags |= REC_ENTER_FLAG_INJECT_SEA; + else if (vcpu_el1_is_32bit(vcpu)) inject_abt32(vcpu, false, addr); else inject_abt64(vcpu, false, addr); diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c index ab365e839874..bff89d47a4d5 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" @@ -136,14 +137,21 @@ 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); } /* * 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 |= REC_ENTER_FLAG_EMULATED_MMIO; + else + kvm_incr_pc(vcpu); return 1; } @@ -162,14 +170,14 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa) * No valid syndrome? Ask userspace for help if it has * volunteered to do so, and bail out otherwise. * - * In the protected VM case, there isn't much userspace can do + * In the protected/realm VM case, there isn't much userspace can do * though, so directly deliver an exception to the guest. */ if (!kvm_vcpu_dabt_isvalid(vcpu)) { trace_kvm_mmio_nisv(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu), kvm_vcpu_get_hfar(vcpu), fault_ipa); - if (vcpu_is_protected(vcpu)) { + if (vcpu_is_protected(vcpu) || vcpu_is_rec(vcpu)) { kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu)); return 1; } diff --git a/arch/arm64/kvm/rme-exit.c b/arch/arm64/kvm/rme-exit.c index aae1adefe1a3..c785005f821f 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> --- Changes since v5: * Inject SEA to the guest is an emulatable MMIO access triggers a data abort. * kvm_handle_mmio_return() - disable kvm_incr_pc() for a REC (as the PC isn't under the host's control) and move the REC_ENTER_EMULATED_MMIO flag setting to this location (as that tells the RMM to skip the instruction). --- arch/arm64/kvm/inject_fault.c | 4 +++- arch/arm64/kvm/mmio.c | 16 ++++++++++++---- arch/arm64/kvm/rme-exit.c | 6 ++++++ 3 files changed, 21 insertions(+), 5 deletions(-)