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Subject[PATCH V17 11/11] arm/arm64: KVM: add guest SEA support
Date
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>
---
arch/arm/include/asm/kvm_arm.h | 10 ++++++++++
arch/arm/include/asm/system_misc.h | 5 +++++
arch/arm64/include/asm/kvm_arm.h | 10 ++++++++++
arch/arm64/include/asm/system_misc.h | 2 ++
arch/arm64/mm/fault.c | 22 ++++++++++++++++++++--
drivers/acpi/apei/ghes.c | 17 +++++++++++------
include/acpi/ghes.h | 2 +-
virt/kvm/arm/mmu.c | 36 +++++++++++++++++++++++++++++++++---
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 a3f0b3d..ebf020b 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 a3d61ad..8c4a89f 100644
--- a/arch/arm/include/asm/system_misc.h
+++ b/arch/arm/include/asm/system_misc.h
@@ -22,6 +22,11 @@

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 6e99978..61d694c 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 bc81243..95aa442 100644
--- a/arch/arm64/include/asm/system_misc.h
+++ b/arch/arm64/include/asm/system_misc.h
@@ -56,6 +56,8 @@ void hook_debug_fault_code(int nr, int (*fn)(unsigned long, unsigned int,
__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 9b4e26f..1ce62cc 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 int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
};

/*
+ * 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 a0ab5f3..7084c97 100644
--- a/drivers/acpi/apei/ghes.c
+++ b/drivers/acpi/apei/ghes.c
@@ -817,17 +817,22 @@ static int ghes_notify_sci(struct notifier_block *this,
#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 95305ae..9f26e01 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 313ee64..521e737 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"

@@ -1418,6 +1419,25 @@ static void handle_access_fault(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
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
@@ -1440,19 +1460,29 @@ 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",
--
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project.
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