[RFC PATCH 15/28] KVM: arm64: Handle realm MMIO emulation

Steven Price
2023-01-27T11:32:50Z

MMIO emulation for a realm cannot be done directly with the VM's
registers as they are protected from the host. However the RMM interface
provides a structure member for providing the read/written value and
we can transfer this to the appropriate VCPU's register entry and then
depend on the generic MMIO handling code in KVM.

Signed-off-by: Steven Price <steven.price@arm.com>
---
arch/arm64/kvm/mmio.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c
index 3dd38a151d2a..c4879fa3a8d3 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"
@@ -109,6 +110,9 @@ int kvm_handle_mmio_return(struct kvm_vcpu *vcpu)
&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->entry.gprs[0] = data;
}

/*
@@ -179,6 +183,9 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
run->mmio.len = len;
vcpu->mmio_needed = 1;

+ if (vcpu_is_rec(vcpu))
+ vcpu->arch.rec.run->entry.flags |= RMI_EMULATED_MMIO;
+
if (!ret) {
/* We handled the access successfully in the kernel. */
if (!is_write)
--
2.34.1