Since the host is called from the hyp run loop, we can use that context
to identify calls from the host rather than checking VTTBR_EL2, which
will be used for the host's stage 2 in future.
Moving this to C also allows for more flexibiliy e.g. in applying
policies, such as forbidding HVC_RESET_VECTORS, based on the current
state of the hypervisor and removes the special casing for nVHE in the
exception handler.
Control over arch workaround 2 is made available to the host, the same
as any other vcpu.
Signed-off-by: Andrew Scull <ascull at google.com>
---
arch/arm64/kvm/hyp/hyp-entry.S | 1 -
arch/arm64/kvm/hyp/nvhe/host.S | 26 +--------------
arch/arm64/kvm/hyp/nvhe/hyp-init.S | 13 ++++++--
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 51 +++++++++++++++++++++++++++++-
4 files changed, 62 insertions(+), 29 deletions(-)
diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S
index b7a1ea221f6e..db54f84003ec 100644
--- a/arch/arm64/kvm/hyp/hyp-entry.S
+++ b/arch/arm64/kvm/hyp/hyp-entry.S
@@ -24,7 +24,6 @@ el1_sync: // Guest trapped into EL2
ccmp x0, #ESR_ELx_EC_HVC32, #4, ne
b.ne el1_trap
-el1_hvc_guest:
/*
* Fastest possible path for ARM_SMCCC_ARCH_WORKAROUND_1.
* The workaround has already been applied on the host,
diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S
index 40620c1c87b8..68d425b7bd62 100644
--- a/arch/arm64/kvm/hyp/nvhe/host.S
+++ b/arch/arm64/kvm/hyp/nvhe/host.S
@@ -95,31 +95,7 @@ SYM_FUNC_END(__hyp_do_panic)
.macro valid_host_el1_sync_vect
.align 7
- stp x0, x1, [sp, #-16]!
- mrs x0, esr_el2
- lsr x0, x0, #ESR_ELx_EC_SHIFT
- cmp x0, #ESR_ELx_EC_HVC64
- ldp x0, x1, [sp], #16
- b.ne __host_exit
-
- /* Check for a stub HVC call */
- cmp x0, #HVC_STUB_HCALL_NR
- b.hs __host_exit
-
- /*
- * Compute the idmap address of __kvm_handle_stub_hvc and
- * jump there. Since we use kimage_voffset, do not use the
- * HYP VA for __kvm_handle_stub_hvc, but the kernel VA instead
- * (by loading it from the constant pool).
- *
- * Preserve x0-x4, which may contain stub parameters.
- */
- ldr x5, =__kvm_handle_stub_hvc
- ldr_l x6, kimage_voffset
-
- /* x5 = __pa(x5) */
- sub x5, x5, x6
- br x5
+ b __host_exit
.endm
.macro invalid_host_el2_vect
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
index 47224dc62c51..40b5aa95c194 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S
@@ -16,6 +16,9 @@
#include <asm/sysreg.h>
#include <asm/virt.h>
+#include <asm/kvm_asm.h>
+#include <asm/kvm_ptrauth.h>
+
.text
.pushsection .hyp.idmap.text, "ax"
@@ -138,6 +141,7 @@ SYM_CODE_START(__kvm_handle_stub_hvc)
cmp x0, #HVC_SOFT_RESTART
b.ne 1f
+SYM_INNER_LABEL(__kvm_handle_stub_hvc_soft_restart, SYM_L_GLOBAL)
/* This is where we're about to jump, staying at EL2 */
msr elr_el2, x1
mov x0, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT | PSR_MODE_EL2h)
@@ -150,8 +154,13 @@ SYM_CODE_START(__kvm_handle_stub_hvc)
b reset
1: cmp x0, #HVC_RESET_VECTORS
- b.ne 1f
+ b.ne 3f
+ b 2f
+
+SYM_INNER_LABEL(__kvm_handle_stub_hvc_reset_vectors, SYM_L_GLOBAL)
+ restore_callee_saved_regs x5
+2:
/*
* Set the HVC_RESET_VECTORS return code before entering the common
* path so that we do not clobber x0-x2 in case we are coming via
@@ -172,7 +181,7 @@ reset:
msr vbar_el2, x5
eret
-1: /* Bad stub call */
+3: /* Bad stub call */
mov_q x0, HVC_STUB_ERR
eret
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index 78d7afcefbb8..302333ea96eb 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -14,6 +14,52 @@
#include <kvm/arm_hypercalls.h>
+typedef __noreturn unsigned long (*stub_hvc_handler_t)
+ (unsigned long, unsigned long, unsigned long, unsigned long,
+ unsigned long, struct kvm_cpu_context *);
+
+extern char __kvm_handle_stub_hvc_soft_restart[];
+extern char __kvm_handle_stub_hvc_reset_vectors[];
+
+static void handle_stub_hvc(unsigned long func_id,
+ struct kvm_cpu_context *host_ctxt)
+{
+ char *stub_hvc_handler_kern_va;
+ stub_hvc_handler_t stub_hvc_handler;
+
+ /*
+ * The handlers of the supported stub HVCs disable the MMU so they must
+ * be called in the idmap. We compute the idmap address by subtracting
+ * kimage_voffset from the kernel VA handler.
+ */
+ switch (func_id) {
+ case HVC_SOFT_RESTART:
+ asm volatile("ldr %0, =%1"
+ : "=r" (stub_hvc_handler_kern_va)
+ : "S" (__kvm_handle_stub_hvc_soft_restart));
+ break;
+ case HVC_RESET_VECTORS:
+ asm volatile("ldr %0, =%1"
+ : "=r" (stub_hvc_handler_kern_va)
+ : "S" (__kvm_handle_stub_hvc_reset_vectors));
+ break;
+ default:
+ host_ctxt->regs.regs[0] = HVC_STUB_ERR;
+ return;
+ }
+
+ stub_hvc_handler = (stub_hvc_handler_t)
+ (stub_hvc_handler_kern_va - kimage_voffset);
+
+ /* Preserve x0-x4, which may contain stub parameters. */
+ stub_hvc_handler(func_id,
+ host_ctxt->regs.regs[1],
+ host_ctxt->regs.regs[2],
+ host_ctxt->regs.regs[3],
+ host_ctxt->regs.regs[4],
+ host_ctxt);
+}
+
static void handle_host_hcall(unsigned long func_id,
struct kvm_cpu_context *host_ctxt)
{
@@ -118,5 +164,8 @@ void handle_trap(struct kvm_cpu_context *host_ctxt) {
hyp_panic();
func_id = host_ctxt->regs.regs[0];
- handle_host_hcall(func_id, host_ctxt);
+ if (func_id < HVC_STUB_HCALL_NR)
+ handle_stub_hvc(func_id, host_ctxt);
+ else
+ handle_host_hcall(func_id, host_ctxt);
}
--
2.28.0.220.ged08abb693-goog