KVM: arm64: Add offset for hyp VA <-> PA conversion

Add a host-initialized constant to KVM nVHE hyp code for converting
between EL2 linear map virtual addresses and physical addresses.
Also add `__hyp_pa` macro that performs the conversion.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20201202184122.26046-18-dbrazdil@google.com

diff --git a/arch/arm64/kvm/hyp/nvhe/psci-relay.c b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
index 61375d4571c29467e1480d5b49514430458c8325..70b42f433449074d7d3f499053e155f0a473582b 100644 (file)
--- a/arch/arm64/kvm/hyp/nvhe/psci-relay.c
+++ b/arch/arm64/kvm/hyp/nvhe/psci-relay.c
@@ -18,6 +18,9 @@
 /* Config options set by the host. */
 __ro_after_init u32 kvm_host_psci_version;
 __ro_after_init struct psci_0_1_function_ids kvm_host_psci_0_1_function_ids;
+__ro_after_init s64 hyp_physvirt_offset;
+
+#define __hyp_pa(x) ((phys_addr_t)((x)) + hyp_physvirt_offset)
 
 static u64 get_psci_func_id(struct kvm_cpu_context *host_ctxt)
 {

diff --git a/arch/arm64/kvm/va_layout.c b/arch/arm64/kvm/va_layout.c
index d61117805de06cf54b8bfff6690a59f7a30d7e02..16aa8615c279f9d72b8063411f5aa27bb7756412 100644 (file)
--- a/arch/arm64/kvm/va_layout.c
+++ b/arch/arm64/kvm/va_layout.c
@@ -23,6 +23,30 @@ static u8 tag_lsb;
 static u64 tag_val;
 static u64 va_mask;
 
+/*
+ * Compute HYP VA by using the same computation as kern_hyp_va().
+ */
+static u64 __early_kern_hyp_va(u64 addr)
+{
+       addr &= va_mask;
+       addr |= tag_val << tag_lsb;
+       return addr;
+}
+
+/*
+ * Store a hyp VA <-> PA offset into a hyp-owned variable.
+ */
+static void init_hyp_physvirt_offset(void)
+{
+       extern s64 kvm_nvhe_sym(hyp_physvirt_offset);
+       u64 kern_va, hyp_va;
+
+       /* Compute the offset from the hyp VA and PA of a random symbol. */
+       kern_va = (u64)kvm_ksym_ref(__hyp_text_start);
+       hyp_va = __early_kern_hyp_va(kern_va);
+       CHOOSE_NVHE_SYM(hyp_physvirt_offset) = (s64)__pa(kern_va) - (s64)hyp_va;
+}
+
 /*
  * We want to generate a hyp VA with the following format (with V ==
  * vabits_actual):
@@ -54,6 +78,8 @@ __init void kvm_compute_layout(void)
                tag_val |= get_random_long() & GENMASK_ULL(vabits_actual - 2, tag_lsb);
        }
        tag_val >>= tag_lsb;
+
+       init_hyp_physvirt_offset();
 }
 
 static u32 compute_instruction(int n, u32 rd, u32 rn)
@@ -151,9 +177,7 @@ void kvm_patch_vector_branch(struct alt_instr *alt,
        /*
         * Compute HYP VA by using the same computation as kern_hyp_va()
         */
-       addr = (uintptr_t)kvm_ksym_ref(__kvm_hyp_vector);
-       addr &= va_mask;
-       addr |= tag_val << tag_lsb;
+       addr = __early_kern_hyp_va((u64)kvm_ksym_ref(__kvm_hyp_vector));
 
        /* Use PC[10:7] to branch to the same vector in KVM */
        addr |= ((u64)origptr & GENMASK_ULL(10, 7));