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KVM: arm64: Drop pkvm_mem_transition for host/hyp sharing
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Simplify the __pkvm_host_{un}share_hyp() paths by not using the
pkvm_mem_transition machinery. As there are the last users of the
do_share()/do_unshare(), remove all the now-unused code as well.

No functional changes intended.

Signed-off-by: Quentin Perret <qperret@google.com>
Link: https://lore.kernel.org/r/20250110121936.1559655-3-qperret@google.com
Signed-off-by: Marc Zyngier <maz@kernel.org>
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Quentin Perret authored and Marc Zyngier committed Jan 12, 2025
1 parent 7a06888 commit 7cbf7c3
Showing 1 changed file with 34 additions and 285 deletions.
319 changes: 34 additions & 285 deletions arch/arm64/kvm/hyp/nvhe/mem_protect.c
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Original file line number Diff line number Diff line change
Expand Up @@ -685,36 +685,6 @@ static int host_request_owned_transition(u64 *completer_addr,
return __host_check_page_state_range(addr, size, PKVM_PAGE_OWNED);
}

static int host_request_unshare(u64 *completer_addr,
const struct pkvm_mem_transition *tx)
{
u64 size = tx->nr_pages * PAGE_SIZE;
u64 addr = tx->initiator.addr;

*completer_addr = tx->initiator.host.completer_addr;
return __host_check_page_state_range(addr, size, PKVM_PAGE_SHARED_OWNED);
}

static int host_initiate_share(u64 *completer_addr,
const struct pkvm_mem_transition *tx)
{
u64 size = tx->nr_pages * PAGE_SIZE;
u64 addr = tx->initiator.addr;

*completer_addr = tx->initiator.host.completer_addr;
return __host_set_page_state_range(addr, size, PKVM_PAGE_SHARED_OWNED);
}

static int host_initiate_unshare(u64 *completer_addr,
const struct pkvm_mem_transition *tx)
{
u64 size = tx->nr_pages * PAGE_SIZE;
u64 addr = tx->initiator.addr;

*completer_addr = tx->initiator.host.completer_addr;
return __host_set_page_state_range(addr, size, PKVM_PAGE_OWNED);
}

static int host_initiate_donation(u64 *completer_addr,
const struct pkvm_mem_transition *tx)
{
Expand Down Expand Up @@ -802,31 +772,6 @@ static bool __hyp_ack_skip_pgtable_check(const struct pkvm_mem_transition *tx)
tx->initiator.id != PKVM_ID_HOST);
}

static int hyp_ack_share(u64 addr, const struct pkvm_mem_transition *tx,
enum kvm_pgtable_prot perms)
{
u64 size = tx->nr_pages * PAGE_SIZE;

if (perms != PAGE_HYP)
return -EPERM;

if (__hyp_ack_skip_pgtable_check(tx))
return 0;

return __hyp_check_page_state_range(addr, size, PKVM_NOPAGE);
}

static int hyp_ack_unshare(u64 addr, const struct pkvm_mem_transition *tx)
{
u64 size = tx->nr_pages * PAGE_SIZE;

if (tx->initiator.id == PKVM_ID_HOST && hyp_page_count((void *)addr))
return -EBUSY;

return __hyp_check_page_state_range(addr, size,
PKVM_PAGE_SHARED_BORROWED);
}

static int hyp_ack_donation(u64 addr, const struct pkvm_mem_transition *tx)
{
u64 size = tx->nr_pages * PAGE_SIZE;
Expand All @@ -837,24 +782,6 @@ static int hyp_ack_donation(u64 addr, const struct pkvm_mem_transition *tx)
return __hyp_check_page_state_range(addr, size, PKVM_NOPAGE);
}

static int hyp_complete_share(u64 addr, const struct pkvm_mem_transition *tx,
enum kvm_pgtable_prot perms)
{
void *start = (void *)addr, *end = start + (tx->nr_pages * PAGE_SIZE);
enum kvm_pgtable_prot prot;

prot = pkvm_mkstate(perms, PKVM_PAGE_SHARED_BORROWED);
return pkvm_create_mappings_locked(start, end, prot);
}

static int hyp_complete_unshare(u64 addr, const struct pkvm_mem_transition *tx)
{
u64 size = tx->nr_pages * PAGE_SIZE;
int ret = kvm_pgtable_hyp_unmap(&pkvm_pgtable, addr, size);

return (ret != size) ? -EFAULT : 0;
}

static int hyp_complete_donation(u64 addr,
const struct pkvm_mem_transition *tx)
{
Expand Down Expand Up @@ -885,180 +812,6 @@ static int __guest_check_page_state_range(struct pkvm_hyp_vcpu *vcpu, u64 addr,
return check_page_state_range(&vm->pgt, addr, size, &d);
}

static int check_share(struct pkvm_mem_share *share)
{
const struct pkvm_mem_transition *tx = &share->tx;
u64 completer_addr;
int ret;

switch (tx->initiator.id) {
case PKVM_ID_HOST:
ret = host_request_owned_transition(&completer_addr, tx);
break;
default:
ret = -EINVAL;
}

if (ret)
return ret;

switch (tx->completer.id) {
case PKVM_ID_HYP:
ret = hyp_ack_share(completer_addr, tx, share->completer_prot);
break;
case PKVM_ID_FFA:
/*
* We only check the host; the secure side will check the other
* end when we forward the FFA call.
*/
ret = 0;
break;
default:
ret = -EINVAL;
}

return ret;
}

static int __do_share(struct pkvm_mem_share *share)
{
const struct pkvm_mem_transition *tx = &share->tx;
u64 completer_addr;
int ret;

switch (tx->initiator.id) {
case PKVM_ID_HOST:
ret = host_initiate_share(&completer_addr, tx);
break;
default:
ret = -EINVAL;
}

if (ret)
return ret;

switch (tx->completer.id) {
case PKVM_ID_HYP:
ret = hyp_complete_share(completer_addr, tx, share->completer_prot);
break;
case PKVM_ID_FFA:
/*
* We're not responsible for any secure page-tables, so there's
* nothing to do here.
*/
ret = 0;
break;
default:
ret = -EINVAL;
}

return ret;
}

/*
* do_share():
*
* The page owner grants access to another component with a given set
* of permissions.
*
* Initiator: OWNED => SHARED_OWNED
* Completer: NOPAGE => SHARED_BORROWED
*/
static int do_share(struct pkvm_mem_share *share)
{
int ret;

ret = check_share(share);
if (ret)
return ret;

return WARN_ON(__do_share(share));
}

static int check_unshare(struct pkvm_mem_share *share)
{
const struct pkvm_mem_transition *tx = &share->tx;
u64 completer_addr;
int ret;

switch (tx->initiator.id) {
case PKVM_ID_HOST:
ret = host_request_unshare(&completer_addr, tx);
break;
default:
ret = -EINVAL;
}

if (ret)
return ret;

switch (tx->completer.id) {
case PKVM_ID_HYP:
ret = hyp_ack_unshare(completer_addr, tx);
break;
case PKVM_ID_FFA:
/* See check_share() */
ret = 0;
break;
default:
ret = -EINVAL;
}

return ret;
}

static int __do_unshare(struct pkvm_mem_share *share)
{
const struct pkvm_mem_transition *tx = &share->tx;
u64 completer_addr;
int ret;

switch (tx->initiator.id) {
case PKVM_ID_HOST:
ret = host_initiate_unshare(&completer_addr, tx);
break;
default:
ret = -EINVAL;
}

if (ret)
return ret;

switch (tx->completer.id) {
case PKVM_ID_HYP:
ret = hyp_complete_unshare(completer_addr, tx);
break;
case PKVM_ID_FFA:
/* See __do_share() */
ret = 0;
break;
default:
ret = -EINVAL;
}

return ret;
}

/*
* do_unshare():
*
* The page owner revokes access from another component for a range of
* pages which were previously shared using do_share().
*
* Initiator: SHARED_OWNED => OWNED
* Completer: SHARED_BORROWED => NOPAGE
*/
static int do_unshare(struct pkvm_mem_share *share)
{
int ret;

ret = check_unshare(share);
if (ret)
return ret;

return WARN_ON(__do_unshare(share));
}

static int check_donation(struct pkvm_mem_donation *donation)
{
const struct pkvm_mem_transition *tx = &donation->tx;
Expand Down Expand Up @@ -1149,31 +902,29 @@ static int do_donate(struct pkvm_mem_donation *donation)

int __pkvm_host_share_hyp(u64 pfn)
{
u64 phys = hyp_pfn_to_phys(pfn);
void *virt = __hyp_va(phys);
enum kvm_pgtable_prot prot;
u64 size = PAGE_SIZE;
int ret;
u64 host_addr = hyp_pfn_to_phys(pfn);
u64 hyp_addr = (u64)__hyp_va(host_addr);
struct pkvm_mem_share share = {
.tx = {
.nr_pages = 1,
.initiator = {
.id = PKVM_ID_HOST,
.addr = host_addr,
.host = {
.completer_addr = hyp_addr,
},
},
.completer = {
.id = PKVM_ID_HYP,
},
},
.completer_prot = PAGE_HYP,
};

host_lock_component();
hyp_lock_component();

ret = do_share(&share);
ret = __host_check_page_state_range(phys, size, PKVM_PAGE_OWNED);
if (ret)
goto unlock;
if (IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) {
ret = __hyp_check_page_state_range((u64)virt, size, PKVM_NOPAGE);
if (ret)
goto unlock;
}

prot = pkvm_mkstate(PAGE_HYP, PKVM_PAGE_SHARED_BORROWED);
WARN_ON(pkvm_create_mappings_locked(virt, virt + size, prot));
WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED));

unlock:
hyp_unlock_component();
host_unlock_component();

Expand All @@ -1182,31 +933,29 @@ int __pkvm_host_share_hyp(u64 pfn)

int __pkvm_host_unshare_hyp(u64 pfn)
{
u64 phys = hyp_pfn_to_phys(pfn);
u64 virt = (u64)__hyp_va(phys);
u64 size = PAGE_SIZE;
int ret;
u64 host_addr = hyp_pfn_to_phys(pfn);
u64 hyp_addr = (u64)__hyp_va(host_addr);
struct pkvm_mem_share share = {
.tx = {
.nr_pages = 1,
.initiator = {
.id = PKVM_ID_HOST,
.addr = host_addr,
.host = {
.completer_addr = hyp_addr,
},
},
.completer = {
.id = PKVM_ID_HYP,
},
},
.completer_prot = PAGE_HYP,
};

host_lock_component();
hyp_lock_component();

ret = do_unshare(&share);
ret = __host_check_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED);
if (ret)
goto unlock;
ret = __hyp_check_page_state_range(virt, size, PKVM_PAGE_SHARED_BORROWED);
if (ret)
goto unlock;
if (hyp_page_count((void *)virt)) {
ret = -EBUSY;
goto unlock;
}

WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, virt, size) != size);
WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_OWNED));

unlock:
hyp_unlock_component();
host_unlock_component();

Expand Down

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