[PATCH 07/16] KVM: arm64: Compute a protected vCPU's fine-grained traps at EL2

[Fuad Tabba <fuad.tabba@linux.dev>]

pKVM sets a protected vCPU's HCR_EL2, MDCR_EL2 and HCRX_EL2 at EL2 from
the VM's ID registers, but never computes its fine-grained traps, which
stay 0. That traps every register with a negative-polarity trap bit, so
a feature such as S1PIE can't be advertised to a protected VM: EL2
would inject an UNDEF for the guest's accesses to PIR_EL1.

Link config.c into the nVHE hyp and compute the VM's FGU masks and the
vCPU's fine-grained traps there, under vm_table_lock, once the ID
registers are set. The init-time check of the feature maps stays out of
the hyp, since it prints and the host runs it anyway.

A protected vCPU then traps the registers of the features it doesn't
support, as a non-protected vCPU does. Its TCR_EL1 writes also get the
AmpereOne AC03_CPU_38 masking again, which protected vCPUs lost when the
erratum's trap moved into the per-vCPU fine-grained traps.

Fixes: fb10ddf35c1cc ("KVM: arm64: Compute per-vCPU FGTs at vcpu_load()")
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/kvm/config.c          | 12 +++++++-----
 arch/arm64/kvm/hyp/nvhe/Makefile |  1 +
 arch/arm64/kvm/hyp/nvhe/pkvm.c   |  2 ++
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/kvm/config.c b/arch/arm64/kvm/config.c
index c65cf1dd27330..27ee8188fd76d 100644
--- a/arch/arm64/kvm/config.c
+++ b/arch/arm64/kvm/config.c
@@ -1395,6 +1395,12 @@ static const struct reg_bits_to_feat_map ich_hfgitr_feat_map[] = {
 static const DECLARE_FEAT_MAP_FGT(ich_hfgitr_desc, ich_hfgitr_masks,
 				  ich_hfgitr_feat_map, FEAT_GCIE);
 
+static u64 reg_feat_map_bits(const struct reg_bits_to_feat_map *map)
+{
+	return map->flags & MASKS_POINTER ? (map->masks->mask | map->masks->nmask) : map->bits;
+}
+
+#ifndef __KVM_NVHE_HYPERVISOR__
 static void __init check_feat_map(const struct reg_bits_to_feat_map *map,
 				  int map_size, u64 resx, const char *str)
 {
@@ -1414,11 +1420,6 @@ static void __init check_feat_map(const struct reg_bits_to_feat_map *map,
 			str, mask ^ ~resx);
 }
 
-static u64 reg_feat_map_bits(const struct reg_bits_to_feat_map *map)
-{
-	return map->flags & MASKS_POINTER ? (map->masks->mask | map->masks->nmask) : map->bits;
-}
-
 static void __init check_reg_desc(const struct reg_feat_map_desc *r)
 {
 	check_feat_map(r->bit_feat_map, r->bit_feat_map_sz,
@@ -1451,6 +1452,7 @@ void __init check_feature_map(void)
 	check_reg_desc(&ich_hfgwtr_desc);
 	check_reg_desc(&ich_hfgitr_desc);
 }
+#endif
 
 static const struct reg_feat_map_desc *idreg_feat_maps[] = {
 	&id_aa64mmfr3_el1_desc,
diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index 56a7e2c05f73a..06d7d8618d89f 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -27,6 +27,7 @@ hyp-obj-y := timer-sr.o sysreg-sr.o debug-sr.o switch.o tlb.o hyp-init.o host.o
 	 cache.o setup.o mm.o mem_protect.o sys_regs.o pkvm.o stacktrace.o ffa.o
 hyp-obj-y += ../vgic-v3-sr.o ../aarch32.o ../vgic-v2-cpuif-proxy.o ../entry.o \
 	 ../hyp-entry.o ../exception.o ../pgtable.o ../vgic-v5-sr.o
+hyp-obj-y += ../../config.o
 hyp-obj-y += ../../../kernel/smccc-call.o
 hyp-obj-$(CONFIG_LIST_HARDENED) += list_debug.o
 hyp-obj-$(CONFIG_NVHE_EL2_TRACING) += clock.o trace.o events.o
diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index fba8dfe6389d6..465d963d6ff57 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
@@ -206,6 +206,8 @@ static int pkvm_vcpu_init_traps(struct pkvm_hyp_vcpu *hyp_vcpu)
 	pvm_init_traps_hcr(vcpu);
 	pvm_init_traps_mdcr(vcpu);
 	vcpu_set_hcrx(vcpu);
+	kvm_init_fgu(vcpu->kvm);
+	kvm_vcpu_load_fgt(vcpu);
 
 	return 0;
 }
-- 
2.47.3