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Marc Zyngier
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KVM: arm64: nv: Add emulation of AT S12E{0,1}{R,W}
On the face of it, AT S12E{0,1}{R,W} is pretty simple. It is the combination of AT S1E{0,1}{R,W}, followed by an extra S2 walk. However, there is a great deal of complexity coming from combining the S1 and S2 attributes to report something consistent in PAR_EL1. This is an absolute mine field, and I have a splitting headache. Signed-off-by: Marc Zyngier <[email protected]>
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‎arch/arm64/include/asm/kvm_asm.h

Lines changed: 1 addition & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -238,6 +238,7 @@ extern int __kvm_tlbi_s1e2(struct kvm_s2_mmu *mmu, u64 va, u64 sys_encoding);
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extern void __kvm_timer_set_cntvoff(u64 cntvoff);
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extern void __kvm_at_s1e01(struct kvm_vcpu *vcpu, u32 op, u64 vaddr);
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extern void __kvm_at_s1e2(struct kvm_vcpu *vcpu, u32 op, u64 vaddr);
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extern void __kvm_at_s12(struct kvm_vcpu *vcpu, u32 op, u64 vaddr);
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extern int __kvm_vcpu_run(struct kvm_vcpu *vcpu);
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‎arch/arm64/kvm/at.c

Lines changed: 253 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -71,6 +71,200 @@ static bool at_s1e1p_fast(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
7171
return fail;
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}
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74+
#define MEMATTR(ic, oc) (MEMATTR_##oc << 4 | MEMATTR_##ic)
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#define MEMATTR_NC 0b0100
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#define MEMATTR_Wt 0b1000
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#define MEMATTR_Wb 0b1100
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#define MEMATTR_WbRaWa 0b1111
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#define MEMATTR_IS_DEVICE(m) (((m) & GENMASK(7, 4)) == 0)
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static u8 s2_memattr_to_attr(u8 memattr)
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{
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memattr &= 0b1111;
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switch (memattr) {
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case 0b0000:
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case 0b0001:
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case 0b0010:
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case 0b0011:
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return memattr << 2;
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case 0b0100:
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return MEMATTR(Wb, Wb);
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case 0b0101:
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return MEMATTR(NC, NC);
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case 0b0110:
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return MEMATTR(Wt, NC);
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case 0b0111:
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return MEMATTR(Wb, NC);
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case 0b1000:
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/* Reserved, assume NC */
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return MEMATTR(NC, NC);
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case 0b1001:
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return MEMATTR(NC, Wt);
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case 0b1010:
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return MEMATTR(Wt, Wt);
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case 0b1011:
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return MEMATTR(Wb, Wt);
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case 0b1100:
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/* Reserved, assume NC */
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return MEMATTR(NC, NC);
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case 0b1101:
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return MEMATTR(NC, Wb);
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case 0b1110:
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return MEMATTR(Wt, Wb);
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case 0b1111:
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return MEMATTR(Wb, Wb);
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default:
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unreachable();
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}
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}
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static u8 combine_s1_s2_attr(u8 s1, u8 s2)
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{
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bool transient;
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u8 final = 0;
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/* Upgrade transient s1 to non-transient to simplify things */
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switch (s1) {
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case 0b0001 ... 0b0011: /* Normal, Write-Through Transient */
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transient = true;
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s1 = MEMATTR_Wt | (s1 & GENMASK(1,0));
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break;
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case 0b0101 ... 0b0111: /* Normal, Write-Back Transient */
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transient = true;
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s1 = MEMATTR_Wb | (s1 & GENMASK(1,0));
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break;
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default:
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transient = false;
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}
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/* S2CombineS1AttrHints() */
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if ((s1 & GENMASK(3, 2)) == MEMATTR_NC ||
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(s2 & GENMASK(3, 2)) == MEMATTR_NC)
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final = MEMATTR_NC;
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else if ((s1 & GENMASK(3, 2)) == MEMATTR_Wt ||
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(s2 & GENMASK(3, 2)) == MEMATTR_Wt)
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final = MEMATTR_Wt;
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else
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final = MEMATTR_Wb;
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if (final != MEMATTR_NC) {
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/* Inherit RaWa hints form S1 */
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if (transient) {
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switch (s1 & GENMASK(3, 2)) {
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case MEMATTR_Wt:
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final = 0;
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break;
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case MEMATTR_Wb:
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final = MEMATTR_NC;
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break;
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}
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}
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final |= s1 & GENMASK(1, 0);
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}
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return final;
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}
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#define ATTR_NSH 0b00
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#define ATTR_RSV 0b01
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#define ATTR_OSH 0b10
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#define ATTR_ISH 0b11
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static u8 compute_sh(u8 attr, u64 desc)
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{
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u8 sh;
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/* Any form of device, as well as NC has SH[1:0]=0b10 */
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if (MEMATTR_IS_DEVICE(attr) || attr == MEMATTR(NC, NC))
182+
return ATTR_OSH;
183+
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sh = FIELD_GET(PTE_SHARED, desc);
185+
if (sh == ATTR_RSV) /* Reserved, mapped to NSH */
186+
sh = ATTR_NSH;
187+
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return sh;
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}
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static u64 compute_par_s12(struct kvm_vcpu *vcpu, u64 s1_par,
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struct kvm_s2_trans *tr)
193+
{
194+
u8 s1_parattr, s2_memattr, final_attr;
195+
u64 par;
196+
197+
/* If S2 has failed to translate, report the damage */
198+
if (tr->esr) {
199+
par = SYS_PAR_EL1_RES1;
200+
par |= SYS_PAR_EL1_F;
201+
par |= SYS_PAR_EL1_S;
202+
par |= FIELD_PREP(SYS_PAR_EL1_FST, tr->esr);
203+
return par;
204+
}
205+
206+
s1_parattr = FIELD_GET(SYS_PAR_EL1_ATTR, s1_par);
207+
s2_memattr = FIELD_GET(GENMASK(5, 2), tr->desc);
208+
209+
if (__vcpu_sys_reg(vcpu, HCR_EL2) & HCR_FWB) {
210+
if (!kvm_has_feat(vcpu->kvm, ID_AA64PFR2_EL1, MTEPERM, IMP))
211+
s2_memattr &= ~BIT(3);
212+
213+
/* Combination of R_VRJSW and R_RHWZM */
214+
switch (s2_memattr) {
215+
case 0b0101:
216+
if (MEMATTR_IS_DEVICE(s1_parattr))
217+
final_attr = s1_parattr;
218+
else
219+
final_attr = MEMATTR(NC, NC);
220+
break;
221+
case 0b0110:
222+
case 0b1110:
223+
final_attr = MEMATTR(WbRaWa, WbRaWa);
224+
break;
225+
case 0b0111:
226+
case 0b1111:
227+
/* Preserve S1 attribute */
228+
final_attr = s1_parattr;
229+
break;
230+
case 0b0100:
231+
case 0b1100:
232+
case 0b1101:
233+
/* Reserved, do something non-silly */
234+
final_attr = s1_parattr;
235+
break;
236+
default:
237+
/* MemAttr[2]=0, Device from S2 */
238+
final_attr = s2_memattr & GENMASK(1,0) << 2;
239+
}
240+
} else {
241+
/* Combination of R_HMNDG, R_TNHFM and R_GQFSF */
242+
u8 s2_parattr = s2_memattr_to_attr(s2_memattr);
243+
244+
if (MEMATTR_IS_DEVICE(s1_parattr) ||
245+
MEMATTR_IS_DEVICE(s2_parattr)) {
246+
final_attr = min(s1_parattr, s2_parattr);
247+
} else {
248+
/* At this stage, this is memory vs memory */
249+
final_attr = combine_s1_s2_attr(s1_parattr & 0xf,
250+
s2_parattr & 0xf);
251+
final_attr |= combine_s1_s2_attr(s1_parattr >> 4,
252+
s2_parattr >> 4) << 4;
253+
}
254+
}
255+
256+
if ((__vcpu_sys_reg(vcpu, HCR_EL2) & HCR_CD) &&
257+
!MEMATTR_IS_DEVICE(final_attr))
258+
final_attr = MEMATTR(NC, NC);
259+
260+
par = FIELD_PREP(SYS_PAR_EL1_ATTR, final_attr);
261+
par |= tr->output & GENMASK(47, 12);
262+
par |= FIELD_PREP(SYS_PAR_EL1_SH,
263+
compute_sh(final_attr, tr->desc));
264+
265+
return par;
266+
}
267+
74268
/*
75269
* Return the PAR_EL1 value as the result of a valid translation.
76270
*
@@ -215,3 +409,62 @@ void __kvm_at_s1e2(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
215409

216410
vcpu_write_sys_reg(vcpu, par, PAR_EL1);
217411
}
412+
413+
void __kvm_at_s12(struct kvm_vcpu *vcpu, u32 op, u64 vaddr)
414+
{
415+
struct kvm_s2_trans out = {};
416+
u64 ipa, par;
417+
bool write;
418+
int ret;
419+
420+
/* Do the stage-1 translation */
421+
switch (op) {
422+
case OP_AT_S12E1R:
423+
op = OP_AT_S1E1R;
424+
write = false;
425+
break;
426+
case OP_AT_S12E1W:
427+
op = OP_AT_S1E1W;
428+
write = true;
429+
break;
430+
case OP_AT_S12E0R:
431+
op = OP_AT_S1E0R;
432+
write = false;
433+
break;
434+
case OP_AT_S12E0W:
435+
op = OP_AT_S1E0W;
436+
write = true;
437+
break;
438+
default:
439+
WARN_ON_ONCE(1);
440+
return;
441+
}
442+
443+
__kvm_at_s1e01(vcpu, op, vaddr);
444+
par = vcpu_read_sys_reg(vcpu, PAR_EL1);
445+
if (par & SYS_PAR_EL1_F)
446+
return;
447+
448+
/*
449+
* If we only have a single stage of translation (E2H=0 or
450+
* TGE=1), exit early. Same thing if {VM,DC}=={0,0}.
451+
*/
452+
if (!vcpu_el2_e2h_is_set(vcpu) || vcpu_el2_tge_is_set(vcpu) ||
453+
!(vcpu_read_sys_reg(vcpu, HCR_EL2) & (HCR_VM | HCR_DC)))
454+
return;
455+
456+
/* Do the stage-2 translation */
457+
ipa = (par & GENMASK_ULL(47, 12)) | (vaddr & GENMASK_ULL(11, 0));
458+
out.esr = 0;
459+
ret = kvm_walk_nested_s2(vcpu, ipa, &out);
460+
if (ret < 0)
461+
return;
462+
463+
/* Check the access permission */
464+
if (!out.esr &&
465+
((!write && !out.readable) || (write && !out.writable)))
466+
out.esr = ESR_ELx_FSC_PERM | (out.level & 0x3);
467+
468+
par = compute_par_s12(vcpu, par, &out);
469+
vcpu_write_sys_reg(vcpu, par, PAR_EL1);
470+
}

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