ARM: KVM: introduce per-vcpu HYP Configuration Register

So far, KVM/ARM used a fixed HCR configuration per guest, except for
the VI/VF/VA bits to control the interrupt in absence of VGIC.

With the upcoming need to dynamically reconfigure trapping, it becomes
necessary to allow the HCR to be changed on a per-vcpu basis.

The fix here is to mimic what KVM/arm64 already does: a per vcpu HCR
field, initialized at setup time.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>

5 files changed, 11 insertions, 10 deletions

diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
index 1d3153c7eb41..a843e74a384c 100644
--- a/arch/arm/include/asm/kvm_arm.h
+++ b/arch/arm/include/asm/kvm_arm.h
@@ -69,7 +69,6 @@
 #define HCR_GUEST_MASK (HCR_TSC | HCR_TSW | HCR_TWI | HCR_VM | HCR_BSU_IS | \
                         HCR_FB | HCR_TAC | HCR_AMO | HCR_IMO | HCR_FMO | \
                         HCR_TWE | HCR_SWIO | HCR_TIDCP)
-#define HCR_VIRT_EXCP_MASK (HCR_VA | HCR_VI | HCR_VF)
 
 /* System Control Register (SCTLR) bits */
 #define SCTLR_TE        (1 << 30)
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 098f7dd6d564..09af14999c9b 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -101,6 +101,12 @@ struct kvm_vcpu_arch {
         /* The CPU type we expose to the VM */
         u32 midr;
 
+        /* HYP trapping configuration */
+        u32 hcr;
+
+        /* Interrupt related fields */
+        u32 irq_lines;          /* IRQ and FIQ levels */
+
         /* Exception Information */
         struct kvm_vcpu_fault_info fault;
 
@@ -128,9 +134,6 @@ struct kvm_vcpu_arch {
         /* IO related fields */
         struct kvm_decode mmio_decode;
 
-        /* Interrupt related fields */
-        u32 irq_lines;          /* IRQ and FIQ levels */
-
         /* Cache some mmu pages needed inside spinlock regions */
         struct kvm_mmu_memory_cache mmu_page_cache;
 
diff --git a/arch/arm/kernel/asm-offsets.c b/arch/arm/kernel/asm-offsets.c
index ded041711beb..85598b5d1efd 100644
--- a/arch/arm/kernel/asm-offsets.c
+++ b/arch/arm/kernel/asm-offsets.c
@@ -174,6 +174,7 @@ int main(void)
   DEFINE(VCPU_FIQ_REGS,         offsetof(struct kvm_vcpu, arch.regs.fiq_regs));
   DEFINE(VCPU_PC,               offsetof(struct kvm_vcpu, arch.regs.usr_regs.ARM_pc));
   DEFINE(VCPU_CPSR,             offsetof(struct kvm_vcpu, arch.regs.usr_regs.ARM_cpsr));
+  DEFINE(VCPU_HCR,              offsetof(struct kvm_vcpu, arch.hcr));
   DEFINE(VCPU_IRQ_LINES,        offsetof(struct kvm_vcpu, arch.irq_lines));
   DEFINE(VCPU_HSR,              offsetof(struct kvm_vcpu, arch.fault.hsr));
   DEFINE(VCPU_HxFAR,            offsetof(struct kvm_vcpu, arch.fault.hxfar));
diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
index 2786eae10c0d..b23a59c1c522 100644
--- a/arch/arm/kvm/guest.c
+++ b/arch/arm/kvm/guest.c
@@ -38,6 +38,7 @@ struct kvm_stats_debugfs_item debugfs_entries[] = {
 
 int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 {
+        vcpu->arch.hcr = HCR_GUEST_MASK;
         return 0;
 }
 
diff --git a/arch/arm/kvm/interrupts_head.S b/arch/arm/kvm/interrupts_head.S
index 6f18695a09cb..a37270d7d4d6 100644
--- a/arch/arm/kvm/interrupts_head.S
+++ b/arch/arm/kvm/interrupts_head.S
@@ -597,17 +597,14 @@ vcpu	.req	r0		@ vcpu pointer always in r0
 
 /* Enable/Disable: stage-2 trans., trap interrupts, trap wfi, trap smc */
 .macro configure_hyp_role operation
-        mrc     p15, 4, r2, c1, c1, 0   @ HCR
-        bic     r2, r2, #HCR_VIRT_EXCP_MASK
-        ldr     r3, =HCR_GUEST_MASK
         .if \operation == vmentry
-        orr     r2, r2, r3
+        ldr     r2, [vcpu, #VCPU_HCR]
         ldr     r3, [vcpu, #VCPU_IRQ_LINES]
         orr     r2, r2, r3
         .else
-        bic     r2, r2, r3
+        mov     r2, #0
         .endif
-        mcr     p15, 4, r2, c1, c1, 0
+        mcr     p15, 4, r2, c1, c1, 0   @ HCR
 .endm
 
 .macro load_vcpu