arm/arm64: KVM: add guest SEA support

Currently external aborts are unsupported by the guest abort
handling. Add handling for SEAs so that the host kernel reports
SEAs which occur in the guest kernel.

When an SEA occurs in the guest kernel, the guest exits and is
routed to kvm_handle_guest_abort(). Prior to this patch, a print
message of an unsupported FSC would be printed and nothing else
would happen. With this patch, the code gets routed to the APEI
handling of SEAs in the host kernel to report the SEA information.

Signed-off-by: Tyler Baicar <tbaicar@codeaurora.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <cdall@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

8 files changed, 92 insertions, 12 deletions

diff --git a/arch/arm/include/asm/kvm_arm.h b/arch/arm/include/asm/kvm_arm.h
index a3f0b3d50089..ebf020b02bc8 100644
--- a/arch/arm/include/asm/kvm_arm.h
+++ b/arch/arm/include/asm/kvm_arm.h
@@ -187,6 +187,16 @@
 #define FSC_FAULT       (0x04)
 #define FSC_ACCESS      (0x08)
 #define FSC_PERM        (0x0c)
+#define FSC_SEA         (0x10)
+#define FSC_SEA_TTW0    (0x14)
+#define FSC_SEA_TTW1    (0x15)
+#define FSC_SEA_TTW2    (0x16)
+#define FSC_SEA_TTW3    (0x17)
+#define FSC_SECC        (0x18)
+#define FSC_SECC_TTW0   (0x1c)
+#define FSC_SECC_TTW1   (0x1d)
+#define FSC_SECC_TTW2   (0x1e)
+#define FSC_SECC_TTW3   (0x1f)
 
 /* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */
 #define HPFAR_MASK      (~0xf)
diff --git a/arch/arm/include/asm/system_misc.h b/arch/arm/include/asm/system_misc.h
index a3d61ad984af..8c4a89f5ce7d 100644
--- a/arch/arm/include/asm/system_misc.h
+++ b/arch/arm/include/asm/system_misc.h
@@ -22,6 +22,11 @@ extern void (*arm_pm_idle)(void);
 
 extern unsigned int user_debug;
 
+static inline int handle_guest_sea(phys_addr_t addr, unsigned int esr)
+{
+        return -1;
+}
+
 #endif /* !__ASSEMBLY__ */
 
 #endif /* __ASM_ARM_SYSTEM_MISC_H */
diff --git a/arch/arm64/include/asm/kvm_arm.h b/arch/arm64/include/asm/kvm_arm.h
index 6e99978e83bd..61d694c2eae5 100644
--- a/arch/arm64/include/asm/kvm_arm.h
+++ b/arch/arm64/include/asm/kvm_arm.h
@@ -204,6 +204,16 @@
 #define FSC_FAULT       ESR_ELx_FSC_FAULT
 #define FSC_ACCESS      ESR_ELx_FSC_ACCESS
 #define FSC_PERM        ESR_ELx_FSC_PERM
+#define FSC_SEA         ESR_ELx_FSC_EXTABT
+#define FSC_SEA_TTW0    (0x14)
+#define FSC_SEA_TTW1    (0x15)
+#define FSC_SEA_TTW2    (0x16)
+#define FSC_SEA_TTW3    (0x17)
+#define FSC_SECC        (0x18)
+#define FSC_SECC_TTW0   (0x1c)
+#define FSC_SECC_TTW1   (0x1d)
+#define FSC_SECC_TTW2   (0x1e)
+#define FSC_SECC_TTW3   (0x1f)
 
 /* Hyp Prefetch Fault Address Register (HPFAR/HDFAR) */
 #define HPFAR_MASK      (~UL(0xf))
diff --git a/arch/arm64/include/asm/system_misc.h b/arch/arm64/include/asm/system_misc.h
index bc812435bc76..95aa4423247d 100644
--- a/arch/arm64/include/asm/system_misc.h
+++ b/arch/arm64/include/asm/system_misc.h
@@ -56,6 +56,8 @@ extern void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
         __show_ratelimited;                                             \
 })
 
+int handle_guest_sea(phys_addr_t addr, unsigned int esr);
+
 #endif  /* __ASSEMBLY__ */
 
 #endif  /* __ASM_SYSTEM_MISC_H */
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 07481af15fd7..a8c9f2db20ba 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -532,6 +532,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 {
         struct siginfo info;
         const struct fault_info *inf;
+        int ret = 0;
 
         inf = esr_to_fault_info(esr);
         pr_err("Synchronous External Abort: %s (0x%08x) at 0x%016lx\n",
@@ -546,7 +547,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
                 if (interrupts_enabled(regs))
                         nmi_enter();
 
-                ghes_notify_sea();
+                ret = ghes_notify_sea();
 
                 if (interrupts_enabled(regs))
                         nmi_exit();
@@ -561,7 +562,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
                 info.si_addr  = (void __user *)addr;
         arm64_notify_die("", regs, &info, esr);
 
-        return 0;
+        return ret;
 }
 
 static const struct fault_info fault_info[] = {
@@ -632,6 +633,23 @@ static const struct fault_info fault_info[] = {
 };
 
 /*
+ * Handle Synchronous External Aborts that occur in a guest kernel.
+ *
+ * The return value will be zero if the SEA was successfully handled
+ * and non-zero if there was an error processing the error or there was
+ * no error to process.
+ */
+int handle_guest_sea(phys_addr_t addr, unsigned int esr)
+{
+        int ret = -ENOENT;
+
+        if (IS_ENABLED(CONFIG_ACPI_APEI_SEA))
+                ret = ghes_notify_sea();
+
+        return ret;
+}
+
+/*
  * Dispatch a data abort to the relevant handler.
  */
 asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr,
diff --git a/drivers/acpi/apei/ghes.c b/drivers/acpi/apei/ghes.c
index 5073d035bb6e..bc717bdf50f1 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -816,17 +816,22 @@ static struct notifier_block ghes_notifier_sci = {
 #ifdef CONFIG_ACPI_APEI_SEA
 static LIST_HEAD(ghes_sea);
 
-void ghes_notify_sea(void)
+/*
+ * Return 0 only if one of the SEA error sources successfully reported an error
+ * record sent from the firmware.
+ */
+int ghes_notify_sea(void)
 {
         struct ghes *ghes;
+        int ret = -ENOENT;
 
-        /*
-         * synchronize_rcu() will wait for nmi_exit(), so no need to
-         * rcu_read_lock().
-         */
+        rcu_read_lock();
         list_for_each_entry_rcu(ghes, &ghes_sea, list) {
-                ghes_proc(ghes);
+                if (!ghes_proc(ghes))
+                        ret = 0;
         }
+        rcu_read_unlock();
+        return ret;
 }
 
 static void ghes_sea_add(struct ghes *ghes)
diff --git a/include/acpi/ghes.h b/include/acpi/ghes.h
index 95305aeb13ff..9f26e01186ae 100644
--- a/include/acpi/ghes.h
+++ b/include/acpi/ghes.h
@@ -113,6 +113,6 @@ static inline void *acpi_hest_get_next(struct acpi_hest_generic_data *gdata)
         return (void *)(gdata) + acpi_hest_get_record_size(gdata);
 }
 
-void ghes_notify_sea(void);
+int ghes_notify_sea(void);
 
 #endif /* GHES_H */
diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c
index a2d63247d1bb..bde0cdd60997 100644
--- a/virt/kvm/arm/mmu.c
+++ b/virt/kvm/arm/mmu.c
@@ -29,6 +29,7 @@
 #include <asm/kvm_asm.h>
 #include <asm/kvm_emulate.h>
 #include <asm/virt.h>
+#include <asm/system_misc.h>
 
 #include "trace.h"
 
@@ -1427,6 +1428,25 @@ out:
                 kvm_set_pfn_accessed(pfn);
 }
 
+static bool is_abort_sea(unsigned long fault_status)
+{
+        switch (fault_status) {
+        case FSC_SEA:
+        case FSC_SEA_TTW0:
+        case FSC_SEA_TTW1:
+        case FSC_SEA_TTW2:
+        case FSC_SEA_TTW3:
+        case FSC_SECC:
+        case FSC_SECC_TTW0:
+        case FSC_SECC_TTW1:
+        case FSC_SECC_TTW2:
+        case FSC_SECC_TTW3:
+                return true;
+        default:
+                return false;
+        }
+}
+
 /**
  * kvm_handle_guest_abort - handles all 2nd stage aborts
  * @vcpu:       the VCPU pointer
@@ -1449,19 +1469,29 @@ int kvm_handle_guest_abort(struct kvm_vcpu *vcpu, struct kvm_run *run)
         gfn_t gfn;
         int ret, idx;
 
+        fault_status = kvm_vcpu_trap_get_fault_type(vcpu);
+
+        fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
+
+        /*
+         * The host kernel will handle the synchronous external abort. There
+         * is no need to pass the error into the guest.
+         */
+        if (is_abort_sea(fault_status)) {
+                if (!handle_guest_sea(fault_ipa, kvm_vcpu_get_hsr(vcpu)))
+                        return 1;
+        }
+
         is_iabt = kvm_vcpu_trap_is_iabt(vcpu);
         if (unlikely(!is_iabt && kvm_vcpu_dabt_isextabt(vcpu))) {
                 kvm_inject_vabt(vcpu);
                 return 1;
         }
 
-        fault_ipa = kvm_vcpu_get_fault_ipa(vcpu);
-
         trace_kvm_guest_fault(*vcpu_pc(vcpu), kvm_vcpu_get_hsr(vcpu),
                               kvm_vcpu_get_hfar(vcpu), fault_ipa);
 
         /* Check the stage-2 fault is trans. fault or write fault */
-        fault_status = kvm_vcpu_trap_get_fault_type(vcpu);
         if (fault_status != FSC_FAULT && fault_status != FSC_PERM &&
             fault_status != FSC_ACCESS) {
                 kvm_err("Unsupported FSC: EC=%#x xFSC=%#lx ESR_EL2=%#lx\n",