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KVM: arm64: Handle endianness in read helper for emulated PTW

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Implementing FEAT_HAFDBS means adding another descriptor accessor that
needs to deal with the guest-configured endianness. Prepare by moving
the endianness handling into the read accessor and out of the main body
of the S1/S2 PTWs.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Link: https://msgid.link/20251124190158.177318-9-oupton@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>
This commit is contained in:
Oliver Upton
2025-11-24 11:01:50 -08:00
parent 977d1bf15c
commit fabf321cba
2 changed files with 39 additions and 18 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
arch/arm64/kvm/at.c
View File

@@ -362,6 +362,24 @@ transfault:
return -EFAULT; return -EFAULT;
} }
static int kvm_read_s1_desc(struct kvm_vcpu *vcpu, u64 pa, u64 *desc,
struct s1_walk_info *wi)
{
u64 val;
int r;
r = kvm_read_guest(vcpu->kvm, pa, &val, sizeof(val));
if (r)
return r;
if (wi->be)
*desc = be64_to_cpu((__force __be64)val);
else
*desc = le64_to_cpu((__force __le64)val);
return 0;
}
static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi, static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
struct s1_walk_result *wr, u64 va) struct s1_walk_result *wr, u64 va)
{ {
@@ -414,17 +432,12 @@ static int walk_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
return ret; return ret;
} }
ret = kvm_read_guest(vcpu->kvm, ipa, &desc, sizeof(desc)); ret = kvm_read_s1_desc(vcpu, ipa, &desc, wi);
if (ret) { if (ret) {
fail_s1_walk(wr, ESR_ELx_FSC_SEA_TTW(level), false); fail_s1_walk(wr, ESR_ELx_FSC_SEA_TTW(level), false);
return ret; return ret;
} }
if (wi->be)
desc = be64_to_cpu((__force __be64)desc);
else
desc = le64_to_cpu((__force __le64)desc);
/* Invalid descriptor */ /* Invalid descriptor */
if (!(desc & BIT(0))) if (!(desc & BIT(0)))
goto transfault; goto transfault;

32
arch/arm64/kvm/nested.c
View File

@@ -197,9 +197,26 @@ static int check_output_size(struct s2_walk_info *wi, phys_addr_t output)
return 0; return 0;
} }
static int read_guest_s2_desc(struct kvm_vcpu *vcpu, phys_addr_t pa, u64 *desc) static int read_guest_s2_desc(struct kvm_vcpu *vcpu, phys_addr_t pa, u64 *desc,
struct s2_walk_info *wi)
{ {
return kvm_read_guest(vcpu->kvm, pa, desc, sizeof(*desc)); u64 val;
int r;
r = kvm_read_guest(vcpu->kvm, pa, &val, sizeof(val));
if (r)
return r;
/*
* Handle reversedescriptors if endianness differs between the
* host and the guest hypervisor.
*/
if (wi->be)
*desc = be64_to_cpu((__force __be64)val);
else
*desc = le64_to_cpu((__force __le64)val);
return 0;
} }
/* /*
@@ -260,19 +277,10 @@ static int walk_nested_s2_pgd(struct kvm_vcpu *vcpu, phys_addr_t ipa,
>> (addr_bottom - 3); >> (addr_bottom - 3);
paddr = base_addr | index; paddr = base_addr | index;
ret = read_guest_s2_desc(vcpu, paddr, &desc); ret = read_guest_s2_desc(vcpu, paddr, &desc, wi);
if (ret < 0) if (ret < 0)
return ret; return ret;
/*
* Handle reversedescriptors if endianness differs between the
* host and the guest hypervisor.
*/
if (wi->be)
desc = be64_to_cpu((__force __be64)desc);
else
desc = le64_to_cpu((__force __le64)desc);
/* Check for valid descriptor at this point */ /* Check for valid descriptor at this point */
if (!(desc & 1) || ((desc & 3) == 1 && level == 3)) { if (!(desc & 1) || ((desc & 3) == 1 && level == 3)) {
out->esr = compute_fsc(level, ESR_ELx_FSC_FAULT); out->esr = compute_fsc(level, ESR_ELx_FSC_FAULT);