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KVM: arm64: Ignore -EAGAIN when mapping in pages for the pKVM host

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If the host takes a stage-2 translation fault on two CPUs at the same
time, one of them will get back -EAGAIN from the page-table mapping code
when it runs into the mapping installed by the other.

Rather than handle this explicitly in handle_host_mem_abort(), pass the
new KVM_PGTABLE_WALK_IGNORE_EAGAIN flag to kvm_pgtable_stage2_map() from
__host_stage2_idmap() and return -EEXIST if host_stage2_adjust_range()
finds a valid pte. This will avoid having to test for -EAGAIN on the
reclaim path in subsequent patches.

Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Tested-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://patch.msgid.link/20260330144841.26181-11-will@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
This commit is contained in:
Will Deacon 2026-03-30 15:48:11 +01:00 committed by Marc Zyngier
parent f0877a1455
commit 73c55be089
1 changed files with 16 additions and 5 deletions
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21
arch/arm64/kvm/hyp/nvhe/mem_protect.c
View File

@ -461,8 +461,15 @@ static bool range_is_memory(u64 start, u64 end)
static inline int __host_stage2_idmap(u64 start, u64 end,
enum kvm_pgtable_prot prot)
{
/*
* We don't make permission changes to the host idmap after
* initialisation, so we can squash -EAGAIN to save callers
* having to treat it like success in the case that they try to
* map something that is already mapped.
*/
return kvm_pgtable_stage2_map(&host_mmu.pgt, start, end - start, start,
prot, &host_s2_pool, 0);
prot, &host_s2_pool,
KVM_PGTABLE_WALK_IGNORE_EAGAIN);
}
/*
@ -504,7 +511,7 @@ static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range)
return ret;
if (kvm_pte_valid(pte))
return -EAGAIN;
return -EEXIST;
if (pte) {
WARN_ON(addr_is_memory(addr) &&
@ -609,7 +616,6 @@ void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
{
struct kvm_vcpu_fault_info fault;
u64 esr, addr;
int ret = 0;
esr = read_sysreg_el2(SYS_ESR);
if (!__get_fault_info(esr, &fault)) {
@ -628,8 +634,13 @@ void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
BUG_ON(!(fault.hpfar_el2 & HPFAR_EL2_NS));
addr = FIELD_GET(HPFAR_EL2_FIPA, fault.hpfar_el2) << 12;
ret = host_stage2_idmap(addr);
BUG_ON(ret && ret != -EAGAIN);
switch (host_stage2_idmap(addr)) {
case -EEXIST:
case 0:
break;
default:
BUG();
}
}
struct check_walk_data {