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KVM: arm64: Reload vCPU for accesses to OSLAR_EL1

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KVM takes ownership of the debug regs if the guest enables the OS lock,
as it needs to use MDSCR_EL1 to mask debug exceptions. Just reload the
vCPU if the guest toggles the OS lock, relying on kvm_vcpu_load_debug()
to update the debug owner and get the right trap configuration in place.

Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20241219224116.3941496-13-oliver.upton@linux.dev
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Oliver Upton
2024-12-19 14:41:09 -08:00
committed by Marc Zyngier
parent beb470d96c
commit 06d22a9c1b
3 changed files with 15 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
arch/arm64/include/asm/kvm_host.h
View File

@@ -1346,6 +1346,7 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu);
void kvm_arm_clear_debug(struct kvm_vcpu *vcpu);
void kvm_vcpu_load_debug(struct kvm_vcpu *vcpu);
void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu);
void kvm_debug_handle_oslar(struct kvm_vcpu *vcpu, u64 val);
#define kvm_vcpu_os_lock_enabled(vcpu) \
(!!(__vcpu_sys_reg(vcpu, OSLSR_EL1) & OSLSR_EL1_OSLK))

13
arch/arm64/kvm/debug.c
View File

@@ -288,3 +288,16 @@ void kvm_debug_set_guest_ownership(struct kvm_vcpu *vcpu)
vcpu->arch.debug_owner = VCPU_DEBUG_GUEST_OWNED;
}
void kvm_debug_handle_oslar(struct kvm_vcpu *vcpu, u64 val)
{
if (val & OSLAR_EL1_OSLK)
__vcpu_sys_reg(vcpu, OSLSR_EL1) |= OSLSR_EL1_OSLK;
else
__vcpu_sys_reg(vcpu, OSLSR_EL1) &= ~OSLSR_EL1_OSLK;
preempt_disable();
kvm_arch_vcpu_put(vcpu);
kvm_arch_vcpu_load(vcpu, smp_processor_id());
preempt_enable();
}

9
arch/arm64/kvm/sys_regs.c
View File

@@ -570,17 +570,10 @@ static bool trap_oslar_el1(struct kvm_vcpu *vcpu,
struct sys_reg_params *p,
const struct sys_reg_desc *r)
{
u64 oslsr;
if (!p->is_write)
return read_from_write_only(vcpu, p, r);
/* Forward the OSLK bit to OSLSR */
oslsr = __vcpu_sys_reg(vcpu, OSLSR_EL1) & ~OSLSR_EL1_OSLK;
if (p->regval & OSLAR_EL1_OSLK)
oslsr |= OSLSR_EL1_OSLK;
__vcpu_sys_reg(vcpu, OSLSR_EL1) = oslsr;
kvm_debug_handle_oslar(vcpu, p->regval);
return true;
}