diff mbox series

[1/2] KVM: arm64: Clean out the odd handling of completer_addr

Message ID 20221028083448.1998389-2-oliver.upton@linux.dev (mailing list archive)
State New, archived
Headers show
Series KVM: arm64: pKVM memory transitions cleanup | expand

Commit Message

Oliver Upton Oct. 28, 2022, 8:34 a.m. UTC 
The layout of struct pkvm_mem_transition is a bit weird; the destination
address for the transition is actually stashed in the initiator address
context. Even weirder so, that address is thrown inside a union and
return from helpers by use of an out pointer.

Rip out the whole mess and move the destination address into the
destination context sub-struct. No functional change intended.

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
---
 arch/arm64/kvm/hyp/nvhe/mem_protect.c | 70 ++++++++++-----------------
 1 file changed, 25 insertions(+), 45 deletions(-)

Comments

Will Deacon Nov. 10, 2022, 10:42 a.m. UTC | #1 
Hi Oliver,

On Fri, Oct 28, 2022 at 08:34:47AM +0000, Oliver Upton wrote:
> The layout of struct pkvm_mem_transition is a bit weird; the destination
> address for the transition is actually stashed in the initiator address
> context. Even weirder so, that address is thrown inside a union and
> return from helpers by use of an out pointer.
> 
> Rip out the whole mess and move the destination address into the
> destination context sub-struct. No functional change intended.
> 
> Signed-off-by: Oliver Upton <oliver.upton@linux.dev>
> ---
>  arch/arm64/kvm/hyp/nvhe/mem_protect.c | 70 ++++++++++-----------------
>  1 file changed, 25 insertions(+), 45 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> index 1e78acf9662e..3636a24e1b34 100644
> --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> @@ -393,17 +393,12 @@ struct pkvm_mem_transition {
>  		enum pkvm_component_id	id;
>  		/* Address in the initiator's address space */
>  		u64			addr;
> -
> -		union {
> -			struct {
> -				/* Address in the completer's address space */
> -				u64	completer_addr;
> -			} host;
> -		};
>  	} initiator;
>  
>  	struct {
>  		enum pkvm_component_id	id;
> +		/* Address in the completer's address space */
> +		u64			addr;
>  	} completer;
>  };

I'm reasonably sure we'll end up putting this back like we had it as we gain
support for guest-initiatied transitions, where we have to walk the guest
stage-2 page-table to figure out the physical address of the memory being
shared, which is the host (completer's) IPA thanks to the identity mapping
there.

So here's what I'll do: I'll post a v6 of the EL2 state series, and I'll
include this at the end (before the RFC patch) and let Marc decide whether
to go ahead with it. I do agree that it cleans things up for now but, as
above, I think that's likely to be a short-lived change.

Sound reasonable?

Cheers,

Will
diff mbox series

Patch

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 1e78acf9662e..3636a24e1b34 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -393,17 +393,12 @@  struct pkvm_mem_transition {
 		enum pkvm_component_id	id;
 		/* Address in the initiator's address space */
 		u64			addr;
-
-		union {
-			struct {
-				/* Address in the completer's address space */
-				u64	completer_addr;
-			} host;
-		};
 	} initiator;
 
 	struct {
 		enum pkvm_component_id	id;
+		/* Address in the completer's address space */
+		u64			addr;
 	} completer;
 };
 
@@ -471,43 +466,35 @@  static int __host_set_page_state_range(u64 addr, u64 size,
 	return host_stage2_idmap_locked(addr, size, prot);
 }
 
-static int host_request_owned_transition(u64 *completer_addr,
-					 const struct pkvm_mem_transition *tx)
+static int host_request_owned_transition(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_OWNED);
 }
 
-static int host_request_unshare(u64 *completer_addr,
-				const struct pkvm_mem_transition *tx)
+static int host_request_unshare(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)
+static int host_initiate_share(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)
+static int host_initiate_unshare(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);
 }
 
@@ -537,7 +524,7 @@  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,
+static int hyp_ack_share(const struct pkvm_mem_transition *tx,
 			 enum kvm_pgtable_prot perms)
 {
 	u64 size = tx->nr_pages * PAGE_SIZE;
@@ -548,34 +535,35 @@  static int hyp_ack_share(u64 addr, const struct pkvm_mem_transition *tx,
 	if (__hyp_ack_skip_pgtable_check(tx))
 		return 0;
 
-	return __hyp_check_page_state_range(addr, size, PKVM_NOPAGE);
+	return __hyp_check_page_state_range(tx->completer.addr, size, PKVM_NOPAGE);
 }
 
-static int hyp_ack_unshare(u64 addr, const struct pkvm_mem_transition *tx)
+static int hyp_ack_unshare(const struct pkvm_mem_transition *tx)
 {
 	u64 size = tx->nr_pages * PAGE_SIZE;
 
 	if (__hyp_ack_skip_pgtable_check(tx))
 		return 0;
 
-	return __hyp_check_page_state_range(addr, size,
+	return __hyp_check_page_state_range(tx->completer.addr, size,
 					    PKVM_PAGE_SHARED_BORROWED);
 }
 
-static int hyp_complete_share(u64 addr, const struct pkvm_mem_transition *tx,
+static int hyp_complete_share(const struct pkvm_mem_transition *tx,
 			      enum kvm_pgtable_prot perms)
 {
-	void *start = (void *)addr, *end = start + (tx->nr_pages * PAGE_SIZE);
+	void *start = (void *)tx->completer.addr;
+	void *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)
+static int hyp_complete_unshare(const struct pkvm_mem_transition *tx)
 {
 	u64 size = tx->nr_pages * PAGE_SIZE;
-	int ret = kvm_pgtable_hyp_unmap(&pkvm_pgtable, addr, size);
+	int ret = kvm_pgtable_hyp_unmap(&pkvm_pgtable, tx->completer.addr, size);
 
 	return (ret != size) ? -EFAULT : 0;
 }
@@ -583,12 +571,11 @@  static int hyp_complete_unshare(u64 addr, const struct pkvm_mem_transition *tx)
 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);
+		ret = host_request_owned_transition(tx);
 		break;
 	default:
 		ret = -EINVAL;
@@ -599,7 +586,7 @@  static int check_share(struct pkvm_mem_share *share)
 
 	switch (tx->completer.id) {
 	case PKVM_ID_HYP:
-		ret = hyp_ack_share(completer_addr, tx, share->completer_prot);
+		ret = hyp_ack_share(tx, share->completer_prot);
 		break;
 	default:
 		ret = -EINVAL;
@@ -611,12 +598,11 @@  static int check_share(struct pkvm_mem_share *share)
 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);
+		ret = host_initiate_share(tx);
 		break;
 	default:
 		ret = -EINVAL;
@@ -627,7 +613,7 @@  static int __do_share(struct pkvm_mem_share *share)
 
 	switch (tx->completer.id) {
 	case PKVM_ID_HYP:
-		ret = hyp_complete_share(completer_addr, tx, share->completer_prot);
+		ret = hyp_complete_share(tx, share->completer_prot);
 		break;
 	default:
 		ret = -EINVAL;
@@ -659,12 +645,11 @@  static int do_share(struct pkvm_mem_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);
+		ret = host_request_unshare(tx);
 		break;
 	default:
 		ret = -EINVAL;
@@ -675,7 +660,7 @@  static int check_unshare(struct pkvm_mem_share *share)
 
 	switch (tx->completer.id) {
 	case PKVM_ID_HYP:
-		ret = hyp_ack_unshare(completer_addr, tx);
+		ret = hyp_ack_unshare(tx);
 		break;
 	default:
 		ret = -EINVAL;
@@ -687,12 +672,11 @@  static int check_unshare(struct pkvm_mem_share *share)
 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);
+		ret = host_initiate_unshare(tx);
 		break;
 	default:
 		ret = -EINVAL;
@@ -703,7 +687,7 @@  static int __do_unshare(struct pkvm_mem_share *share)
 
 	switch (tx->completer.id) {
 	case PKVM_ID_HYP:
-		ret = hyp_complete_unshare(completer_addr, tx);
+		ret = hyp_complete_unshare(tx);
 		break;
 	default:
 		ret = -EINVAL;
@@ -743,12 +727,10 @@  int __pkvm_host_share_hyp(u64 pfn)
 			.initiator	= {
 				.id	= PKVM_ID_HOST,
 				.addr	= host_addr,
-				.host	= {
-					.completer_addr = hyp_addr,
-				},
 			},
 			.completer	= {
 				.id	= PKVM_ID_HYP,
+				.addr	= hyp_addr,
 			},
 		},
 		.completer_prot	= PAGE_HYP,
@@ -776,12 +758,10 @@  int __pkvm_host_unshare_hyp(u64 pfn)
 			.initiator	= {
 				.id	= PKVM_ID_HOST,
 				.addr	= host_addr,
-				.host	= {
-					.completer_addr = hyp_addr,
-				},
 			},
 			.completer	= {
 				.id	= PKVM_ID_HYP,
+				.addr	= hyp_addr,
 			},
 		},
 		.completer_prot	= PAGE_HYP,