debug-sr.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (C) 2015 - ARM Ltd
  4 * Author: Marc Zyngier <marc.zyngier@arm.com>
  5 */
  6
  7#include <hyp/debug-sr.h>
  8
  9#include <linux/compiler.h>
 10#include <linux/kvm_host.h>
 11
 12#include <asm/debug-monitors.h>
 13#include <asm/kvm_asm.h>
 14#include <asm/kvm_hyp.h>
 15#include <asm/kvm_mmu.h>
 16
 17static void __debug_save_spe(u64 *pmscr_el1)
 18{
 19	u64 reg;
 20
 21	/* Clear pmscr in case of early return */
 22	*pmscr_el1 = 0;
 23
 24	/*
 25	 * At this point, we know that this CPU implements
 26	 * SPE and is available to the host.
 27	 * Check if the host is actually using it ?
 28	 */
 29	reg = read_sysreg_s(SYS_PMBLIMITR_EL1);
 30	if (!(reg & BIT(PMBLIMITR_EL1_E_SHIFT)))
 31		return;
 32
 33	/* Yes; save the control register and disable data generation */
 34	*pmscr_el1 = read_sysreg_el1(SYS_PMSCR);
 35	write_sysreg_el1(0, SYS_PMSCR);
 36	isb();
 37
 38	/* Now drain all buffered data to memory */
 39	psb_csync();
 40}
 41
 42static void __debug_restore_spe(u64 pmscr_el1)
 43{
 44	if (!pmscr_el1)
 45		return;
 46
 47	/* The host page table is installed, but not yet synchronised */
 48	isb();
 49
 50	/* Re-enable data generation */
 51	write_sysreg_el1(pmscr_el1, SYS_PMSCR);
 52}
 53
 54static void __trace_do_switch(u64 *saved_trfcr, u64 new_trfcr)
 55{
 56	*saved_trfcr = read_sysreg_el1(SYS_TRFCR);
 57	write_sysreg_el1(new_trfcr, SYS_TRFCR);
 58}
 59
 60static bool __trace_needs_drain(void)
 61{
 62	if (is_protected_kvm_enabled() && host_data_test_flag(HAS_TRBE))
 63		return read_sysreg_s(SYS_TRBLIMITR_EL1) & TRBLIMITR_EL1_E;
 64
 65	return host_data_test_flag(TRBE_ENABLED);
 66}
 67
 68static bool __trace_needs_switch(void)
 69{
 70	return host_data_test_flag(TRBE_ENABLED) ||
 71	       host_data_test_flag(EL1_TRACING_CONFIGURED);
 72}
 73
 74static void __trace_switch_to_guest(void)
 75{
 76	/* Unsupported with TRBE so disable */
 77	if (host_data_test_flag(TRBE_ENABLED))
 78		*host_data_ptr(trfcr_while_in_guest) = 0;
 79
 80	__trace_do_switch(host_data_ptr(host_debug_state.trfcr_el1),
 81			  *host_data_ptr(trfcr_while_in_guest));
 82
 83	if (__trace_needs_drain()) {
 84		isb();
 85		tsb_csync();
 86	}
 87}
 88
 89static void __trace_switch_to_host(void)
 90{
 91	__trace_do_switch(host_data_ptr(trfcr_while_in_guest),
 92			  *host_data_ptr(host_debug_state.trfcr_el1));
 93}
 94
 95static void __debug_save_brbe(u64 *brbcr_el1)
 96{
 97	*brbcr_el1 = 0;
 98
 99	/* Check if the BRBE is enabled */
100	if (!(read_sysreg_el1(SYS_BRBCR) & (BRBCR_ELx_E0BRE | BRBCR_ELx_ExBRE)))
101		return;
102
103	/*
104	 * Prohibit branch record generation while we are in guest.
105	 * Since access to BRBCR_EL1 is trapped, the guest can't
106	 * modify the filtering set by the host.
107	 */
108	*brbcr_el1 = read_sysreg_el1(SYS_BRBCR);
109	write_sysreg_el1(0, SYS_BRBCR);
110}
111
112static void __debug_restore_brbe(u64 brbcr_el1)
113{
114	if (!brbcr_el1)
115		return;
116
117	/* Restore BRBE controls */
118	write_sysreg_el1(brbcr_el1, SYS_BRBCR);
119}
120
121void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu)
122{
123	/* Disable and flush SPE data generation */
124	if (host_data_test_flag(HAS_SPE))
125		__debug_save_spe(host_data_ptr(host_debug_state.pmscr_el1));
126
127	/* Disable BRBE branch records */
128	if (host_data_test_flag(HAS_BRBE))
129		__debug_save_brbe(host_data_ptr(host_debug_state.brbcr_el1));
130
131	if (__trace_needs_switch())
132		__trace_switch_to_guest();
133}
134
135void __debug_switch_to_guest(struct kvm_vcpu *vcpu)
136{
137	__debug_switch_to_guest_common(vcpu);
138}
139
140void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu)
141{
142	if (host_data_test_flag(HAS_SPE))
143		__debug_restore_spe(*host_data_ptr(host_debug_state.pmscr_el1));
144	if (host_data_test_flag(HAS_BRBE))
145		__debug_restore_brbe(*host_data_ptr(host_debug_state.brbcr_el1));
146	if (__trace_needs_switch())
147		__trace_switch_to_host();
148}
149
150void __debug_switch_to_host(struct kvm_vcpu *vcpu)
151{
152	__debug_switch_to_host_common(vcpu);
153}