Re: [PATCH v4 15/15] KVM: arm: enable trapping of all debug registers

On 2015/9/3 0:08, Christoffer Dall wrote: > On Mon, Aug 10, 2015 at 09:26:07PM +0800, Zhichao Huang wrote: >> Enable trapping of the debug registers unconditionally, allowing guests to >> use the debug infrastructure. >> >> Signed-off-by: Zhichao Huang <zhichao

Re: [PATCH v4 01/15] KVM: arm: plug guest debug exploit

On 2015/9/2 19:38, Christoffer Dall wrote: > > I really think that we should read the register, clear the bits you care > about (MDBGen and HDBGen) and then write back the register. > > So, if I recall correctly, this is to avoid having to set HDCR_TDE > below? > > Given Will's concerns about

Re: [PATCH v4 13/15] KVM: arm: keep track of guest use of the debug registers

On 2015/9/3 0:01, Christoffer Dall wrote: > On Mon, Aug 10, 2015 at 09:26:05PM +0800, Zhichao Huang wrote: >> >> -static bool trap_debug32(struct kvm_vcpu *vcpu, >> +/* Indicate whether the guest has enabled any break/watch points or not. */ >> +static bool guest_d

Re: [PATCH v4 10/15] KVM: arm: implement world switch for debug registers

On 2015/9/2 22:53, Christoffer Dall wrote: >> +/* Reads cp14 registers from hardware. >> + * Writes cp14 registers in-order to the CP14 struct pointed to by r10 >> + * >> + * Assumes vcpu pointer in vcpu reg >> + * >> + * Clobbers r2-r12 >> + */ >> +.macro save_debug_state >> +

[PATCH v4 01/15] KVM: arm: plug guest debug exploit

the debug mode(DBGDSCR) in the guest world all the time, preventing the guests to mess with the host state. However, it is a precursor for later patches which will need to do more to world switch debug states while necessary. Cc: sta...@vger.kernel.org Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org

[PATCH v4 00/15] KVM: arm: debug infrastructure support

/kvmarm/2015-May/014847.html [3]: https://lists.cs.columbia.edu/pipermail/kvmarm/2015-June/015167.html Zhichao Huang (15): KVM: arm: plug guest debug exploit KVM: arm: rename pm_fake handler to trap_raz_wi KVM: arm: enable to use the ARM_DSCR_MDBGEN macro from KVM assembly code KVM: arm

[PATCH v4 02/15] KVM: arm: rename pm_fake handler to trap_raz_wi

pm_fake doesn't quite describe what the handler does (ignoring writes and returning 0 for reads). As we're about to use it (a lot) in a different context, rename it with a (admitedly cryptic) name that make sense for all users. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org Reviewed

[PATCH v4 03/15] KVM: arm: enable to use the ARM_DSCR_MDBGEN macro from KVM assembly code

Add #ifndef __ASSEMBLY__ in hw_breakpoint.h, in order to use the ARM_DSCR_MDBGEN macro from KVM assembly code. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org Reviewed-by: Alex Bennee alex.ben...@linaro.org Acked-by: Christoffer Dall christoffer.d...@linaro.org --- arch/arm/include/asm

[PATCH v4 08/15] KVM: arm: add a trace event for cp14 traps

There are too many cp15 traps, so we don't reuse the cp15 trace event but add a new trace event to trace the access of debug registers. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org Acked-by: Christoffer Dall christoffer.d...@linaro.org --- arch/arm/kvm/coproc.c | 14 ++ arch

[PATCH v4 06/15] KVM: arm: add trap handlers for 32-bit debug registers

Add handlers for all the 32-bit debug registers. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_asm.h | 12 arch/arm/include/asm/kvm_host.h | 3 + arch/arm/kernel/asm-offsets.c | 1 + arch/arm/kvm/coproc.c | 124

[PATCH v4 14/15] KVM: arm: implement lazy world switch for debug registers

Avoid world-switching all the debug registers when neither the host nor the guest has configured any [WB]points. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/kvm/interrupts_head.S | 23 +-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git

[PATCH v4 15/15] KVM: arm: enable trapping of all debug registers

Enable trapping of the debug registers unconditionally, allowing guests to use the debug infrastructure. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org Reviewed-by: Christoffer Dall christoffer.d...@linaro.org --- arch/arm/kvm/interrupts_head.S | 2 +- 1 file changed, 1 insertion(+), 1

[PATCH v4 04/15] KVM: arm: common infrastructure for handling AArch32 CP14/CP15

As we're about to trap a bunch of CP14 registers, let's rework the CP15 handling so it can be generalized and work with multiple tables. We stop trapping access here, because we haven't finished our trap handlers. We will enable trapping agian until everything is OK. Signed-off-by: Zhichao Huang

[PATCH v4 12/15] KVM: arm: keep track of host use of the debug registers

Every guest entry, we need to keep track of host use of the debug registers. We only call the function upon guest entry, after preempt_disable() and local_irq_disable(), so there is no race for it. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_asm.h| 3

[PATCH v4 13/15] KVM: arm: keep track of guest use of the debug registers

We trap debug register accesses from guest all the time, and read the BCR/WCR to indicate whether the guest has enabled any break/watch points or not. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_asm.h | 2 ++ arch/arm/kvm/coproc.c | 75

[PATCH v4 11/15] KVM: arm: add a function to keep track of host use of the debug registers

As we're about to implement a lazy world switch for debug registers, we add a function reading the break/watch control variables directly to indicate whether the host has enabled any break/watch points or not. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm

Re: [PATCH v3 08/11] KVM: arm: implement dirty bit mechanism for debug registers

an indication for KVM, and it's low-overhead. We will only call it upon guest entry, so there is also no race for it. On July 7, 2015 6:24:06 PM GMT+08:00, Will Deacon will.dea...@arm.com wrote: On Tue, Jul 07, 2015 at 11:06:57AM +0100, Zhichao Huang wrote: Chazy and me are talking about how

Re: [PATCH v3 08/11] KVM: arm: implement dirty bit mechanism for debug registers

of reading from real hardware registers, and to decide whether we need a world switch or not. Does it acceptable? On July 3, 2015 7:56:11 PM GMT+08:00, Christoffer Dall christoffer.d...@linaro.org wrote: On Fri, Jul 03, 2015 at 05:54:47PM +0800, Zhichao Huang wrote: On June 30, 2015 5:20:20 PM

Re: [PATCH v3 08/11] KVM: arm: implement dirty bit mechanism for debug registers

On June 30, 2015 5:20:20 PM GMT+08:00, Christoffer Dall christoffer.d...@linaro.org wrote: On Mon, Jun 22, 2015 at 06:41:31PM +0800, Zhichao Huang wrote: The trapping code keeps track of the state of the debug registers, allowing for the switch code to implement a lazy switching strategy

Re: [PATCH v3 09/11] KVM: arm: implement lazy world switch for debug registers

On June 30, 2015 9:15:22 PM GMT+08:00, Christoffer Dall christoffer.d...@linaro.org wrote: On Mon, Jun 22, 2015 at 06:41:32PM +0800, Zhichao Huang wrote: Implement switching of the debug registers. While the number of registers is massive, CPUs usually don't implement them all (A15 has 6

Re: [PATCH v3 07/11] KVM: arm: add trap handlers for 64-bit debug registers

On June 30, 2015 9:20:29 PM GMT+08:00, Christoffer Dall christoffer.d...@linaro.org wrote: On Mon, Jun 22, 2015 at 06:41:30PM +0800, Zhichao Huang wrote: Add handlers for all the 64-bit debug registers. There is an overlap between 32 and 64bit registers. Make sure that 64-bit registers

[PATCH v3 08/11] KVM: arm: implement dirty bit mechanism for debug registers

The trapping code keeps track of the state of the debug registers, allowing for the switch code to implement a lazy switching strategy. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_asm.h | 3 +++ arch/arm/include/asm/kvm_host.h | 3 +++ arch/arm/kernel

[PATCH v3 06/11] KVM: arm: add trap handlers for 32-bit debug registers

Add handlers for all the 32-bit debug registers. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_asm.h | 12 arch/arm/include/asm/kvm_host.h | 3 + arch/arm/kernel/asm-offsets.c | 1 + arch/arm/kvm/coproc.c | 122

[PATCH v3 05/11] KVM: arm: check ordering of all system register tables

We now have multiple tables for the various system registers we trap. Make sure we check the order of all of them, as it is critical that we get the order right (been there, done that...). Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/kvm/coproc.c | 26

[PATCH v2 08/11] KVM: arm: implement dirty bit mechanism for debug registers

The trapping code keeps track of the state of the debug registers, allowing for the switch code to implement a lazy switching strategy. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_asm.h | 3 +++ arch/arm/include/asm/kvm_host.h | 3 +++ arch/arm/kernel

[PATCH v2 06/11] KVM: arm: add trap handlers for 32-bit debug registers

Add handlers for all the 32-bit debug registers. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_asm.h | 12 arch/arm/include/asm/kvm_host.h | 3 + arch/arm/kernel/asm-offsets.c | 1 + arch/arm/kvm/coproc.c | 122

[PATCH v2 07/11] KVM: arm: add trap handlers for 64-bit debug registers

Add handlers for all the 64-bit debug registers. There is an overlap between 32 and 64bit registers. Make sure that 64-bit registers preceding 32-bit ones. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/kvm/coproc.c | 12 1 file changed, 12 insertions(+) diff

[PATCH v2 00/11] KVM: arm: debug infrastructure support

reset functions - Disable debug mode if we don't need it to reduce unnecessary switch [1]: https://lists.cs.columbia.edu/pipermail/kvmarm/2015-May/014729.html Zhichao Huang (11): KVM: arm: plug guest debug exploit KVM: arm: rename pm_fake handler to trap_raz_wi KVM: arm: enable to use

[PATCH v2 04/11] KVM: arm: common infrastructure for handling AArch32 CP14/CP15

As we're about to trap a bunch of CP14 registers, let's rework the CP15 handling so it can be generalized and work with multiple tables. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/kvm/coproc.c | 176 ++--- arch/arm/kvm

[PATCH v2 05/11] KVM: arm: check ordering of all system register tables

We now have multiple tables for the various system registers we trap. Make sure we check the order of all of them, as it is critical that we get the order right (been there, done that...). Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/kvm/coproc.c | 26

[PATCH v2 01/11] KVM: arm: plug guest debug exploit

for later patches which will need to do more to world switch debug states while necessary. Cc: sta...@vger.kernel.org Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_coproc.h | 3 +- arch/arm/kvm/coproc.c | 60 +++ arch

[PATCH v2 03/11] KVM: arm: enable to use the ARM_DSCR_MDBGEN macro from KVM assembly code

Add #ifndef __ASSEMBLY__ in hw_breakpoint.h, in order to use the ARM_DSCR_MDBGEN macro from KVM assembly code. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/hw_breakpoint.h | 54 +++- 1 file changed, 29 insertions(+), 25 deletions

[PATCH v2 09/11] KVM: arm: disable debug mode if we don't actually need it.

Until now we enable debug mode all the time even if we don't actually need it. Inspired by the implementation in arm64, disable debug mode if we don't need it. And then we are able to reduce unnecessary registers saving/restoring when the debug mode is disabled. Signed-off-by: Zhichao Huang

[PATCH 06/10] KVM: arm: add trap handlers for 32-bit debug registers

Add handlers for all the 32-bit debug registers. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_asm.h | 12 arch/arm/include/asm/kvm_host.h | 3 + arch/arm/kernel/asm-offsets.c | 1 + arch/arm/kvm/coproc.c | 122

[PATCH 07/10] KVM: arm: add trap handlers for 64-bit debug registers

Add handlers for all the 64-bit debug registers. There is an overlap between 32 and 64bit registers. Make sure that 64-bit registers preceding 32-bit ones. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/kvm/coproc.c | 12 1 file changed, 12 insertions(+) diff

[PATCH 05/10] KVM: arm: check ordering of all system register tables

We now have multiple tables for the various system registers we trap. Make sure we check the order of all of them, as it is critical that we get the order right (been there, done that...). Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/kvm/coproc.c | 26

[PATCH 04/10] KVM: arm: common infrastructure for handling AArch32 CP14/CP15

As we're about to trap a bunch of CP14 registers, let's rework the CP15 handling so it can be generalized and work with multiple tables. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/kvm/coproc.c | 176 ++--- arch/arm/kvm

[PATCH 02/10] KVM: arm: rename pm_fake handler to trap_raz_wi

pm_fake doesn't quite describe what the handler does (ignoring writes and returning 0 for reads). As we're about to use it (a lot) in a different context, rename it with a (admitedly cryptic) name that make sense for all users. Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm

[PATCH 01/10] KVM: arm: plug guest debug exploit

for later patches which will need to do more to world switch debug states while necessary. Cc: sta...@vger.kernel.org Signed-off-by: Zhichao Huang zhichao.hu...@linaro.org --- arch/arm/include/asm/kvm_coproc.h | 3 +- arch/arm/kvm/coproc.c | 60 +++ arch

[PATCH 00/10] KVM: arm: debug infrastructure support

the effort, at least for the time being. This has been tested on a Cortex-A15 platform, running 32bit guests. The patches for this series are based off v4.1-rc3 and can be found at: https://git.linaro.org/people/zhichao.huang/linux.git branch: guest-debug/4.1-rc3-v1 Zhichao Huang (10): KVM: arm: plug

Re: [PATCH v2 06/10] KVM: arm64: guest debug, add SW break point support

On Tue, Mar 31, 2015 at 04:08:04PM +0100, Alex Bennée wrote: This adds support for SW breakpoints inserted by userspace. We do this by trapping all BKPT exceptions in the hypervisor (MDCR_EL2_TDE). why should we trap all debug exceptions? The trap for cp14 register r/w seems enough to record