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arm64: KVM: Enable access to TRBE support for host 

For a nvhe host, the EL2 must allow the EL1&0 translation
regime for TraceBuffer (MDCR_EL2.E2TB == 0b11). This must
be saved/restored over a trip to the guest. Also, before
entering the guest, we must flush any trace data if the
TRBE was enabled. And we must prohibit the generation
of trace while we are in EL1 by clearing the TRFCR_EL1.

For vhe, the EL2 must prevent the EL1 access to the Trace
Buffer.

The MDCR_EL2 bit definitions for TRBE are available here :

  https://developer.arm.com/documentation/ddi0601/2020-12/AArch64-Registers/

Cc: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210405164307.1720226-8-suzuki.poulose@arm.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
This commit is contained in:
Suzuki K Poulose 2021-04-05 17:42:54 +01:00 committed by Mathieu Poirier
parent d2602bb4f5
commit a1319260bf
7 changed files with 65 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
arch/arm64/include/asm/el2_setup.h
View File

@ -65,6 +65,19 @@
// use EL1&0 translation.
.Lskip_spe_\@:
/* Trace buffer */
ubfx x0, x1, #ID_AA64DFR0_TRBE_SHIFT, #4
cbz x0, .Lskip_trace_\@ // Skip if TraceBuffer is not present
mrs_s x0, SYS_TRBIDR_EL1
and x0, x0, TRBIDR_PROG
cbnz x0, .Lskip_trace_\@ // If TRBE is available at EL2
mov x0, #(MDCR_EL2_E2TB_MASK << MDCR_EL2_E2TB_SHIFT)
orr x2, x2, x0 // allow the EL1&0 translation
// to own it.
.Lskip_trace_\@:
msr mdcr_el2, x2 // Configure debug traps
.endm

2
arch/arm64/include/asm/kvm_arm.h
View File

@ -278,6 +278,8 @@
#define CPTR_EL2_DEFAULT CPTR_EL2_RES1
/* Hyp Debug Configuration Register bits */
#define MDCR_EL2_E2TB_MASK (UL(0x3))
#define MDCR_EL2_E2TB_SHIFT (UL(24))
#define MDCR_EL2_TTRF (1 << 19)
#define MDCR_EL2_TPMS (1 << 14)
#define MDCR_EL2_E2PB_MASK (UL(0x3))

3
arch/arm64/include/asm/kvm_host.h
View File

@ -315,6 +315,8 @@ struct kvm_vcpu_arch {
struct kvm_guest_debug_arch regs;
/* Statistical profiling extension */
u64 pmscr_el1;
/* Self-hosted trace */
u64 trfcr_el1;
} host_debug_state;
/* VGIC state */
@ -401,6 +403,7 @@ struct kvm_vcpu_arch {
#define KVM_ARM64_PENDING_EXCEPTION (1 << 8) /* Exception pending */
#define KVM_ARM64_EXCEPT_MASK (7 << 9) /* Target EL/MODE */
#define KVM_ARM64_DEBUG_STATE_SAVE_SPE (1 << 12) /* Save SPE context if active */
#define KVM_ARM64_DEBUG_STATE_SAVE_TRBE (1 << 13) /* Save TRBE context if active */
/*
* When KVM_ARM64_PENDING_EXCEPTION is set, KVM_ARM64_EXCEPT_MASK can

3
arch/arm64/kernel/hyp-stub.S
View File

@ -115,9 +115,10 @@ SYM_CODE_START_LOCAL(mutate_to_vhe)
mrs_s x0, SYS_VBAR_EL12
msr vbar_el1, x0
// Use EL2 translations for SPE and disable access from EL1
// Use EL2 translations for SPE & TRBE and disable access from EL1
mrs x0, mdcr_el2
bic x0, x0, #(MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT)
bic x0, x0, #(MDCR_EL2_E2TB_MASK << MDCR_EL2_E2TB_SHIFT)
msr mdcr_el2, x0
// Transfer the MM state from EL1 to EL2

14
arch/arm64/kvm/debug.c
View File

@ -89,7 +89,7 @@ void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu)
* - Debug ROM Address (MDCR_EL2_TDRA)
* - OS related registers (MDCR_EL2_TDOSA)
* - Statistical profiler (MDCR_EL2_TPMS/MDCR_EL2_E2PB)
* - Self-hosted Trace Filter controls (MDCR_EL2_TTRF)
* - Self-hosted Trace (MDCR_EL2_TTRF/MDCR_EL2_E2TB)
*
* Additionally, KVM only traps guest accesses to the debug registers if
* the guest is not actively using them (see the KVM_ARM64_DEBUG_DIRTY
@ -107,8 +107,8 @@ void kvm_arm_setup_debug(struct kvm_vcpu *vcpu)
trace_kvm_arm_setup_debug(vcpu, vcpu->guest_debug);
/*
* This also clears MDCR_EL2_E2PB_MASK to disable guest access
* to the profiling buffer.
* This also clears MDCR_EL2_E2PB_MASK and MDCR_EL2_E2TB_MASK
* to disable guest access to the profiling and trace buffers
*/
vcpu->arch.mdcr_el2 = __this_cpu_read(mdcr_el2) & MDCR_EL2_HPMN_MASK;
vcpu->arch.mdcr_el2 |= (MDCR_EL2_TPM |
@ -248,9 +248,15 @@ void kvm_arch_vcpu_load_debug_state_flags(struct kvm_vcpu *vcpu)
if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_PMSVER_SHIFT) &&
!(read_sysreg_s(SYS_PMBIDR_EL1) & BIT(SYS_PMBIDR_EL1_P_SHIFT)))
vcpu->arch.flags |= KVM_ARM64_DEBUG_STATE_SAVE_SPE;
/* Check if we have TRBE implemented and available at the host */
if (cpuid_feature_extract_unsigned_field(dfr0, ID_AA64DFR0_TRBE_SHIFT) &&
!(read_sysreg_s(SYS_TRBIDR_EL1) & TRBIDR_PROG))
vcpu->arch.flags |= KVM_ARM64_DEBUG_STATE_SAVE_TRBE;
}
void kvm_arch_vcpu_put_debug_state_flags(struct kvm_vcpu *vcpu)
{
vcpu->arch.flags &= ~KVM_ARM64_DEBUG_STATE_SAVE_SPE;
vcpu->arch.flags &= ~(KVM_ARM64_DEBUG_STATE_SAVE_SPE |
KVM_ARM64_DEBUG_STATE_SAVE_TRBE);
}

34
arch/arm64/kvm/hyp/nvhe/debug-sr.c
View File

@ -52,11 +52,43 @@ static void __debug_restore_spe(u64 pmscr_el1)
write_sysreg_s(pmscr_el1, SYS_PMSCR_EL1);
}
static void __debug_save_trace(u64 *trfcr_el1)
{
*trfcr_el1 = 0;
/* Check if the TRBE is enabled */
if (!(read_sysreg_s(SYS_TRBLIMITR_EL1) & TRBLIMITR_ENABLE))
return;
/*
* Prohibit trace generation while we are in guest.
* Since access to TRFCR_EL1 is trapped, the guest can't
* modify the filtering set by the host.
*/
*trfcr_el1 = read_sysreg_s(SYS_TRFCR_EL1);
write_sysreg_s(0, SYS_TRFCR_EL1);
isb();
/* Drain the trace buffer to memory */
tsb_csync();
dsb(nsh);
}
static void __debug_restore_trace(u64 trfcr_el1)
{
if (!trfcr_el1)
return;
/* Restore trace filter controls */
write_sysreg_s(trfcr_el1, SYS_TRFCR_EL1);
}
void __debug_save_host_buffers_nvhe(struct kvm_vcpu *vcpu)
{
/* Disable and flush SPE data generation */
if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_SPE)
__debug_save_spe(&vcpu->arch.host_debug_state.pmscr_el1);
/* Disable and flush Self-Hosted Trace generation */
if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_TRBE)
__debug_save_trace(&vcpu->arch.host_debug_state.trfcr_el1);
}
void __debug_switch_to_guest(struct kvm_vcpu *vcpu)
@ -68,6 +100,8 @@ void __debug_restore_host_buffers_nvhe(struct kvm_vcpu *vcpu)
{
if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_SPE)
__debug_restore_spe(vcpu->arch.host_debug_state.pmscr_el1);
if (vcpu->arch.flags & KVM_ARM64_DEBUG_STATE_SAVE_TRBE)
__debug_restore_trace(vcpu->arch.host_debug_state.trfcr_el1);
}
void __debug_switch_to_host(struct kvm_vcpu *vcpu)

1
arch/arm64/kvm/hyp/nvhe/switch.c
View File

@ -95,6 +95,7 @@ static void __deactivate_traps(struct kvm_vcpu *vcpu)
mdcr_el2 &= MDCR_EL2_HPMN_MASK;
mdcr_el2 |= MDCR_EL2_E2PB_MASK << MDCR_EL2_E2PB_SHIFT;
mdcr_el2 |= MDCR_EL2_E2TB_MASK << MDCR_EL2_E2TB_SHIFT;
write_sysreg(mdcr_el2, mdcr_el2);
if (is_protected_kvm_enabled())