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KVM: arm64: nv: Honor SError exception routing / masking

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To date KVM has used HCR_EL2.VSE to track the state of a pending SError
for the guest. With this bit set, hardware respects the EL1 exception
routing / masking rules and injects the vSError when appropriate.

This isn't correct for NV guests as hardware is oblivious to vEL2's
intentions for SErrors. Better yet, with FEAT_NV2 the guest can change
the routing behind our back as HCR_EL2 is redirected to memory. Cope
with this mess by:

 - Using a flag (instead of HCR_EL2.VSE) to track the pending SError
   state when SErrors are unconditionally masked for the current context

 - Resampling the routing / masking of a pending SError on every guest
   entry/exit

 - Emulating exception entry when SError routing implies a translation
   regime change

Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250708172532.1699409-7-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
This commit is contained in:
Oliver Upton
2025-07-08 10:25:11 -07:00
parent 9aba641b9e
commit 77ee70a073
11 changed files with 144 additions and 38 deletions
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18
arch/arm64/include/asm/kvm_host.h
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@@ -817,7 +817,7 @@ struct kvm_vcpu_arch {
u8 iflags;
/* State flags for kernel bookkeeping, unused by the hypervisor code */
u8 sflags;
u16 sflags;
/*
* Don't run the guest (internal implementation need).
@@ -953,9 +953,21 @@ struct kvm_vcpu_arch {
__vcpu_flags_preempt_enable(); \
} while (0)
#define __vcpu_test_and_clear_flag(v, flagset, f, m) \
({ \
typeof(v->arch.flagset) set; \
\
set = __vcpu_get_flag(v, flagset, f, m); \
__vcpu_clear_flag(v, flagset, f, m); \
\
set; \
})
#define vcpu_get_flag(v, ...) __vcpu_get_flag((v), __VA_ARGS__)
#define vcpu_set_flag(v, ...) __vcpu_set_flag((v), __VA_ARGS__)
#define vcpu_clear_flag(v, ...) __vcpu_clear_flag((v), __VA_ARGS__)
#define vcpu_test_and_clear_flag(v, ...) \
__vcpu_test_and_clear_flag((v), __VA_ARGS__)
/* KVM_ARM_VCPU_INIT completed */
#define VCPU_INITIALIZED __vcpu_single_flag(cflags, BIT(0))
@@ -1015,6 +1027,8 @@ struct kvm_vcpu_arch {
#define IN_WFI __vcpu_single_flag(sflags, BIT(6))
/* KVM is currently emulating a nested ERET */
#define IN_NESTED_ERET __vcpu_single_flag(sflags, BIT(7))
/* SError pending for nested guest */
#define NESTED_SERROR_PENDING __vcpu_single_flag(sflags, BIT(8))
/* Pointer to the vcpu's SVE FFR for sve_{save,load}_state() */
@@ -1387,8 +1401,6 @@ static inline bool kvm_arm_is_pvtime_enabled(struct kvm_vcpu_arch *vcpu_arch)
return (vcpu_arch->steal.base != INVALID_GPA);
}
void kvm_set_sei_esr(struct kvm_vcpu *vcpu, u64 syndrome);
struct kvm_vcpu *kvm_mpidr_to_vcpu(struct kvm *kvm, unsigned long mpidr);
DECLARE_KVM_HYP_PER_CPU(struct kvm_host_data, kvm_host_data);