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KVM: arm64: Teach address translation about access faults

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It appears that our S1 PTW is completely oblivious of access faults.
Teach the S1 translation code about it.

Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Link: https://lore.kernel.org/r/20250422122612.2675672-3-maz@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier
2025-04-22 13:26:11 +01:00
parent 493b01de72
commit ed648ab804
1 changed files with 21 additions and 5 deletions
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26
arch/arm64/kvm/at.c
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@@ -456,6 +456,11 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
if (check_output_size(desc & GENMASK(47, va_bottom), wi))
goto addrsz;
if (!(desc & PTE_AF)) {
fail_s1_walk(wr, ESR_ELx_FSC_ACCESS_L(level), false);
return -EACCES;
}
va_bottom += contiguous_bit_shift(desc, wi, level);
wr->failed = false;
@@ -1209,7 +1214,8 @@ static u64 handle_at_slow(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
* If the translation is unsuccessful, the value may only contain
* PAR_EL1.F, and cannot be taken at face value. It isn't an
* indication of the translation having failed, only that the fast
* path did not succeed, *unless* it indicates a S1 permission fault.
* path did not succeed, *unless* it indicates a S1 permission or
* access fault.
*/
static u64 __kvm_at_s1e01_fast(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
{
@@ -1312,19 +1318,29 @@ static bool par_check_s1_perm_fault(u64 par)
!(par & SYS_PAR_EL1_S));
}
static bool par_check_s1_access_fault(u64 par)
{
u8 fst = FIELD_GET(SYS_PAR_EL1_FST, par);
return ((fst & ESR_ELx_FSC_TYPE) == ESR_ELx_FSC_ACCESS &&
!(par & SYS_PAR_EL1_S));
}
void __kvm_at_s1e01(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
{
u64 par = __kvm_at_s1e01_fast(vcpu, op, vaddr);
/*
* If PAR_EL1 reports that AT failed on a S1 permission fault, we
* know for sure that the PTW was able to walk the S1 tables and
* there's nothing else to do.
* If PAR_EL1 reports that AT failed on a S1 permission or access
* fault, we know for sure that the PTW was able to walk the S1
* tables and there's nothing else to do.
*
* If AT failed for any other reason, then we must walk the guest S1
* to emulate the instruction.
*/
if ((par & SYS_PAR_EL1_F) && !par_check_s1_perm_fault(par))
if ((par & SYS_PAR_EL1_F) &&
!par_check_s1_perm_fault(par) &&
!par_check_s1_access_fault(par))
par = handle_at_slow(vcpu, op, vaddr);
vcpu_write_sys_reg(vcpu, par, PAR_EL1);