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KVM: arm64: Compute shareability for LPA2

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LPA2 gets the memory access shareability from TCR_ELx instead of
getting it form the descriptors. Store it in the walk info struct
so that it is passed around and evaluated as required.

Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Marc Zyngier 2025-07-27 19:37:01 +01:00
parent e4bd479884
commit c0cc438046
2 changed files with 31 additions and 7 deletions
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1
arch/arm64/include/asm/kvm_nested.h
View File

@ -295,6 +295,7 @@ struct s1_walk_info {
unsigned int pgshift;
unsigned int txsz;
int sl;
u8 sh;
bool as_el0;
bool hpd;
bool e0poe;

37
arch/arm64/kvm/at.c
View File

@ -188,6 +188,12 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
if (!tbi && (u64)sign_extend64(va, 55) != va)
goto addrsz;
wi->sh = (wi->regime == TR_EL2 ?
FIELD_GET(TCR_EL2_SH0_MASK, tcr) :
(va55 ?
FIELD_GET(TCR_SH1_MASK, tcr) :
FIELD_GET(TCR_SH0_MASK, tcr)));
va = (u64)sign_extend64(va, 55);
/* Let's put the MMU disabled case aside immediately */
@ -697,21 +703,36 @@ static u8 combine_s1_s2_attr(u8 s1, u8 s2)
#define ATTR_OSH 0b10
#define ATTR_ISH 0b11
static u8 compute_sh(u8 attr, u64 desc)
static u8 compute_final_sh(u8 attr, u8 sh)
{
u8 sh;
/* Any form of device, as well as NC has SH[1:0]=0b10 */
if (MEMATTR_IS_DEVICE(attr) || attr == MEMATTR(NC, NC))
return ATTR_OSH;
sh = FIELD_GET(PTE_SHARED, desc);
if (sh == ATTR_RSV) /* Reserved, mapped to NSH */
sh = ATTR_NSH;
return sh;
}
static u8 compute_s1_sh(struct s1_walk_info *wi, struct s1_walk_result *wr,
u8 attr)
{
u8 sh;
/*
* non-52bit and LPA have their basic shareability described in the
* descriptor. LPA2 gets it from the corresponding field in TCR,
* conveniently recorded in the walk info.
*/
if (!wi->pa52bit || BIT(wi->pgshift) == SZ_64K)
sh = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S1_SH, wr->desc);
else
sh = wi->sh;
return compute_final_sh(attr, sh);
}
static u8 combine_sh(u8 s1_sh, u8 s2_sh)
{
if (s1_sh == ATTR_OSH || s2_sh == ATTR_OSH)
@ -725,7 +746,7 @@ static u8 combine_sh(u8 s1_sh, u8 s2_sh)
static u64 compute_par_s12(struct kvm_vcpu *vcpu, u64 s1_par,
struct kvm_s2_trans *tr)
{
u8 s1_parattr, s2_memattr, final_attr;
u8 s1_parattr, s2_memattr, final_attr, s2_sh;
u64 par;
/* If S2 has failed to translate, report the damage */
@ -798,11 +819,13 @@ static u64 compute_par_s12(struct kvm_vcpu *vcpu, u64 s1_par,
!MEMATTR_IS_DEVICE(final_attr))
final_attr = MEMATTR(NC, NC);
s2_sh = FIELD_GET(KVM_PTE_LEAF_ATTR_LO_S2_SH, tr->desc);
par = FIELD_PREP(SYS_PAR_EL1_ATTR, final_attr);
par |= tr->output & GENMASK(47, 12);
par |= FIELD_PREP(SYS_PAR_EL1_SH,
combine_sh(FIELD_GET(SYS_PAR_EL1_SH, s1_par),
compute_sh(final_attr, tr->desc)));
compute_final_sh(final_attr, s2_sh)));
return par;
}
@ -856,7 +879,7 @@ static u64 compute_par_s1(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
par |= FIELD_PREP(SYS_PAR_EL1_ATTR, mair);
par |= wr->pa & GENMASK_ULL(47, 12);
sh = compute_sh(mair, wr->desc);
sh = compute_s1_sh(wi, wr, mair);
par |= FIELD_PREP(SYS_PAR_EL1_SH, sh);
}