git: 75cb949228bb - main - arm64/vmm: Add breakpoint and single-stepping support
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Date: Tue, 04 Jun 2024 20:06:30 UTC
The branch main has been updated by markj:
URL: https://cgit.FreeBSD.org/src/commit/?id=75cb949228bb97e49f35fd2b2585293a6b9212aa
commit 75cb949228bb97e49f35fd2b2585293a6b9212aa
Author: Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2024-06-04 18:58:08 +0000
Commit: Mark Johnston <markj@FreeBSD.org>
CommitDate: 2024-06-04 18:58:08 +0000
arm64/vmm: Add breakpoint and single-stepping support
This will be used to implement parts of bhyve's gdb stub.
Three VM capabilities are added, similar to amd64 without monitor mode.
Two cause breakpoint and single-step exceptions to be raised to EL2 and
then down to bhyve. One lets the gdb stub mask hardware interrupts
while single-stepping, since otherwise the guest will handle a timer
interrupt before executing the target instruction and thus fail
to make progress.
Reviewed by: bnovkov, andrew
Sponsored by: Innovate UK
Differential Revision: https://reviews.freebsd.org/D44739
---
sys/arm64/include/vmm.h | 6 +++-
sys/arm64/vmm/arm64.h | 9 ++++++
sys/arm64/vmm/vmm_arm64.c | 79 +++++++++++++++++++++++++++++++++++++++++++++--
sys/arm64/vmm/vmm_stat.c | 2 ++
sys/arm64/vmm/vmm_stat.h | 2 ++
5 files changed, 95 insertions(+), 3 deletions(-)
diff --git a/sys/arm64/include/vmm.h b/sys/arm64/include/vmm.h
index 8e2c9c868635..c06d2ad947e4 100644
--- a/sys/arm64/include/vmm.h
+++ b/sys/arm64/include/vmm.h
@@ -295,9 +295,11 @@ struct vre {
*/
enum vm_cap_type {
VM_CAP_HALT_EXIT,
- VM_CAP_MTRAP_EXIT,
VM_CAP_PAUSE_EXIT,
VM_CAP_UNRESTRICTED_GUEST,
+ VM_CAP_BRK_EXIT,
+ VM_CAP_SS_EXIT,
+ VM_CAP_MASK_HWINTR,
VM_CAP_MAX
};
@@ -312,6 +314,8 @@ enum vm_exitcode {
VM_EXITCODE_PAGING,
VM_EXITCODE_SMCCC,
VM_EXITCODE_DEBUG,
+ VM_EXITCODE_BRK,
+ VM_EXITCODE_SS,
VM_EXITCODE_MAX
};
diff --git a/sys/arm64/vmm/arm64.h b/sys/arm64/vmm/arm64.h
index 43459d14e143..8cfe77dcde6f 100644
--- a/sys/arm64/vmm/arm64.h
+++ b/sys/arm64/vmm/arm64.h
@@ -39,6 +39,9 @@
struct vgic_v3;
struct vgic_v3_cpu;
+/*
+ * Per-vCPU hypervisor state.
+ */
struct hypctx {
struct trapframe tf;
@@ -104,6 +107,12 @@ struct hypctx {
struct vtimer_cpu vtimer_cpu;
+ uint64_t setcaps; /* Currently enabled capabilities. */
+
+ /* vCPU state used to handle guest debugging. */
+ uint64_t debug_spsr; /* Saved guest SPSR */
+ uint64_t debug_mdscr; /* Saved guest MDSCR */
+
struct vgic_v3_regs vgic_v3_regs;
struct vgic_v3_cpu *vgic_cpu;
bool has_exception;
diff --git a/sys/arm64/vmm/vmm_arm64.c b/sys/arm64/vmm/vmm_arm64.c
index e71761f9ccef..e0547bcef914 100644
--- a/sys/arm64/vmm/vmm_arm64.c
+++ b/sys/arm64/vmm/vmm_arm64.c
@@ -700,7 +700,14 @@ handle_el1_sync_excp(struct hypctx *hypctx, struct vm_exit *vme_ret,
arm64_gen_reg_emul_data(esr_iss, vme_ret);
vme_ret->exitcode = VM_EXITCODE_REG_EMUL;
break;
-
+ case EXCP_BRK:
+ vmm_stat_incr(hypctx->vcpu, VMEXIT_BRK, 1);
+ vme_ret->exitcode = VM_EXITCODE_BRK;
+ break;
+ case EXCP_SOFTSTP_EL0:
+ vmm_stat_incr(hypctx->vcpu, VMEXIT_SS, 1);
+ vme_ret->exitcode = VM_EXITCODE_SS;
+ break;
case EXCP_INSN_ABORT_L:
case EXCP_DATA_ABORT_L:
vmm_stat_incr(hypctx->vcpu, esr_ec == EXCP_DATA_ABORT_L ?
@@ -1313,6 +1320,7 @@ vmmops_exception(void *vcpui, uint64_t esr, uint64_t far)
int
vmmops_getcap(void *vcpui, int num, int *retval)
{
+ struct hypctx *hypctx = vcpui;
int ret;
ret = ENOENT;
@@ -1322,6 +1330,11 @@ vmmops_getcap(void *vcpui, int num, int *retval)
*retval = 1;
ret = 0;
break;
+ case VM_CAP_BRK_EXIT:
+ case VM_CAP_SS_EXIT:
+ case VM_CAP_MASK_HWINTR:
+ *retval = (hypctx->setcaps & (1ul << num)) != 0;
+ break;
default:
break;
}
@@ -1332,6 +1345,68 @@ vmmops_getcap(void *vcpui, int num, int *retval)
int
vmmops_setcap(void *vcpui, int num, int val)
{
+ struct hypctx *hypctx = vcpui;
+ int ret;
+
+ ret = 0;
- return (ENOENT);
+ switch (num) {
+ case VM_CAP_BRK_EXIT:
+ if ((val != 0) == (hypctx->setcaps & (1ul << num)) != 0)
+ break;
+ if (val != 0)
+ hypctx->mdcr_el2 |= MDCR_EL2_TDE;
+ else
+ hypctx->mdcr_el2 &= ~MDCR_EL2_TDE;
+ break;
+ case VM_CAP_SS_EXIT:
+ if ((val != 0) == (hypctx->setcaps & (1ul << num)) != 0)
+ break;
+
+ if (val != 0) {
+ hypctx->debug_spsr |= (hypctx->tf.tf_spsr & PSR_SS);
+ hypctx->debug_mdscr |= hypctx->mdscr_el1 &
+ (MDSCR_SS | MDSCR_KDE);
+
+ hypctx->tf.tf_spsr |= PSR_SS;
+ hypctx->mdscr_el1 |= MDSCR_SS | MDSCR_KDE;
+ hypctx->mdcr_el2 |= MDCR_EL2_TDE;
+ } else {
+ hypctx->tf.tf_spsr &= ~PSR_SS;
+ hypctx->tf.tf_spsr |= hypctx->debug_spsr;
+ hypctx->debug_spsr &= ~PSR_SS;
+ hypctx->mdscr_el1 &= ~(MDSCR_SS | MDSCR_KDE);
+ hypctx->mdscr_el1 |= hypctx->debug_mdscr;
+ hypctx->debug_mdscr &= ~(MDSCR_SS | MDSCR_KDE);
+ hypctx->mdcr_el2 &= ~MDCR_EL2_TDE;
+ }
+ break;
+ case VM_CAP_MASK_HWINTR:
+ if ((val != 0) == (hypctx->setcaps & (1ul << num)) != 0)
+ break;
+
+ if (val != 0) {
+ hypctx->debug_spsr |= (hypctx->tf.tf_spsr &
+ (PSR_I | PSR_F));
+ hypctx->tf.tf_spsr |= PSR_I | PSR_F;
+ } else {
+ hypctx->tf.tf_spsr &= ~(PSR_I | PSR_F);
+ hypctx->tf.tf_spsr |= (hypctx->debug_spsr &
+ (PSR_I | PSR_F));
+ hypctx->debug_spsr &= ~(PSR_I | PSR_F);
+ }
+ break;
+ default:
+ ret = ENOENT;
+ break;
+ }
+
+ if (ret == 0) {
+ if (val == 0)
+ hypctx->setcaps &= ~(1ul << num);
+ else
+ hypctx->setcaps |= (1ul << num);
+ }
+
+ return (ret);
}
diff --git a/sys/arm64/vmm/vmm_stat.c b/sys/arm64/vmm/vmm_stat.c
index 858ce980843a..05ece6f30579 100644
--- a/sys/arm64/vmm/vmm_stat.c
+++ b/sys/arm64/vmm/vmm_stat.c
@@ -161,5 +161,7 @@ VMM_STAT(VMEXIT_INSN_ABORT, "number of vmexits for an instruction abort");
VMM_STAT(VMEXIT_UNHANDLED_SYNC, "number of vmexits for an unhandled synchronous exception");
VMM_STAT(VMEXIT_IRQ, "number of vmexits for an irq");
VMM_STAT(VMEXIT_FIQ, "number of vmexits for an interrupt");
+VMM_STAT(VMEXIT_BRK, "number of vmexits for a breakpoint exception");
+VMM_STAT(VMEXIT_SS, "number of vmexits for a single-step exception");
VMM_STAT(VMEXIT_UNHANDLED_EL2, "number of vmexits for an unhandled EL2 exception");
VMM_STAT(VMEXIT_UNHANDLED, "number of vmexits for an unhandled exception");
diff --git a/sys/arm64/vmm/vmm_stat.h b/sys/arm64/vmm/vmm_stat.h
index b0a06ef79253..402fa2f1b1e4 100644
--- a/sys/arm64/vmm/vmm_stat.h
+++ b/sys/arm64/vmm/vmm_stat.h
@@ -140,6 +140,8 @@ VMM_STAT_DECLARE(VMEXIT_INSN_ABORT);
VMM_STAT_DECLARE(VMEXIT_UNHANDLED_SYNC);
VMM_STAT_DECLARE(VMEXIT_IRQ);
VMM_STAT_DECLARE(VMEXIT_FIQ);
+VMM_STAT_DECLARE(VMEXIT_BRK);
+VMM_STAT_DECLARE(VMEXIT_SS);
VMM_STAT_DECLARE(VMEXIT_UNHANDLED_EL2);
VMM_STAT_DECLARE(VMEXIT_UNHANDLED);
#endif