KVM: arm64: Allocate pages for hypervisor FF-A mailboxes

The FF-A proxy code needs to allocate its own buffer pair for
communication with EL3 and for forwarding calls from the host at EL1.

Reserve a couple of pages for this purpose and use them to initialise
the hypervisor's FF-A buffer structure.

Co-developed-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Andrew Walbran <qwandor@google.com>
Signed-off-by: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20230523101828.7328-4-will@kernel.org
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

diff --git a/arch/arm64/include/asm/kvm_pkvm.h b/arch/arm64/include/asm/kvm_pkvm.h
index 01129b0..2b495ec 100644 (file)
--- a/arch/arm64/include/asm/kvm_pkvm.h
+++ b/arch/arm64/include/asm/kvm_pkvm.h
@@ -106,4 +106,12 @@ static inline unsigned long host_s2_pgtable_pages(void)
        return res;
 }
 
+#define KVM_FFA_MBOX_NR_PAGES  1
+
+static inline unsigned long hyp_ffa_proxy_pages(void)
+{
+       /* A page each for the hypervisor's RX and TX mailboxes. */
+       return 2 * KVM_FFA_MBOX_NR_PAGES;
+}
+
 #endif /* __ARM64_KVM_PKVM_H__ */

diff --git a/arch/arm64/kvm/hyp/include/nvhe/ffa.h b/arch/arm64/kvm/hyp/include/nvhe/ffa.h
index 5c9b924..1becb10 100644 (file)
--- a/arch/arm64/kvm/hyp/include/nvhe/ffa.h
+++ b/arch/arm64/kvm/hyp/include/nvhe/ffa.h
@@ -11,7 +11,7 @@
 #define FFA_MIN_FUNC_NUM 0x60
 #define FFA_MAX_FUNC_NUM 0x7F
 
-int hyp_ffa_init(void);
+int hyp_ffa_init(void *pages);
 bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt);
 
 #endif /* __KVM_HYP_FFA_H */

diff --git a/arch/arm64/kvm/hyp/nvhe/ffa.c b/arch/arm64/kvm/hyp/nvhe/ffa.c
index abdcaf9..c85e5d4 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/ffa.c
+++ b/arch/arm64/kvm/hyp/nvhe/ffa.c
@@ -28,8 +28,11 @@
 
 #include <linux/arm-smccc.h>
 #include <linux/arm_ffa.h>
+#include <asm/kvm_pkvm.h>
+
 #include <nvhe/ffa.h>
 #include <nvhe/trap_handler.h>
+#include <nvhe/spinlock.h>
 
 /*
  * "ID value 0 must be returned at the Non-secure physical FF-A instance"
@@ -37,6 +40,19 @@
  */
 #define HOST_FFA_ID    0
 
+struct kvm_ffa_buffers {
+       hyp_spinlock_t lock;
+       void *tx;
+       void *rx;
+};
+
+/*
+ * Note that we don't currently lock these buffers explicitly, instead
+ * relying on the locking of the host FFA buffers as we only have one
+ * client.
+ */
+static struct kvm_ffa_buffers hyp_buffers;
+
 static void ffa_to_smccc_error(struct arm_smccc_res *res, u64 ffa_errno)
 {
        *res = (struct arm_smccc_res) {
@@ -124,7 +140,7 @@ bool kvm_host_ffa_handler(struct kvm_cpu_context *host_ctxt)
        return true;
 }
 
-int hyp_ffa_init(void)
+int hyp_ffa_init(void *pages)
 {
        struct arm_smccc_res res;
 
@@ -145,5 +161,11 @@ int hyp_ffa_init(void)
        if (res.a2 != HOST_FFA_ID)
                return -EINVAL;
 
+       hyp_buffers = (struct kvm_ffa_buffers) {
+               .lock   = __HYP_SPIN_LOCK_UNLOCKED,
+               .tx     = pages,
+               .rx     = pages + (KVM_FFA_MBOX_NR_PAGES * PAGE_SIZE),
+       };
+
        return 0;
 }

diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index c4ca174..bb98630 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -29,6 +29,7 @@ static void *vmemmap_base;
 static void *vm_table_base;
 static void *hyp_pgt_base;
 static void *host_s2_pgt_base;
+static void *ffa_proxy_pages;
 static struct kvm_pgtable_mm_ops pkvm_pgtable_mm_ops;
 static struct hyp_pool hpool;
 
@@ -58,6 +59,11 @@ static int divide_memory_pool(void *virt, unsigned long size)
        if (!host_s2_pgt_base)
                return -ENOMEM;
 
+       nr_pages = hyp_ffa_proxy_pages();
+       ffa_proxy_pages = hyp_early_alloc_contig(nr_pages);
+       if (!ffa_proxy_pages)
+               return -ENOMEM;
+
        return 0;
 }
 
@@ -315,7 +321,7 @@ void __noreturn __pkvm_init_finalise(void)
        if (ret)
                goto out;
 
-       ret = hyp_ffa_init();
+       ret = hyp_ffa_init(ffa_proxy_pages);
        if (ret)
                goto out;
 

diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
index 6e9ece1..994a494 100644 (file)
--- a/arch/arm64/kvm/pkvm.c
+++ b/arch/arm64/kvm/pkvm.c
@@ -78,6 +78,7 @@ void __init kvm_hyp_reserve(void)
        hyp_mem_pages += host_s2_pgtable_pages();
        hyp_mem_pages += hyp_vm_table_pages();
        hyp_mem_pages += hyp_vmemmap_pages(STRUCT_HYP_PAGE_SIZE);
+       hyp_mem_pages += hyp_ffa_proxy_pages();
 
        /*
         * Try to allocate a PMD-aligned region to reduce TLB pressure once