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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v7 00/14] arm/mem_access: Walk guest page tables in SW if mem_access is active
Hi Julien,
Sorry for the late reply.
On 07/31/2017 04:38 PM, Julien Grall wrote:
>
>
> On 18/07/17 13:24, Sergej Proskurin wrote:
>> Hi all,
>
> Hi,
>
>>
>> The function p2m_mem_access_check_and_get_page is called from the function
>> get_page_from_gva if mem_access is active and the hardware-aided translation
>> of
>> the given guest virtual address (gva) into machine address fails. That is, if
>> the stage-2 translation tables constrain access to the guests's page tables,
>> hardware-assisted translation will fail. The idea of the function
>> p2m_mem_access_check_and_get_page is thus to translate the given gva and
>> check
>> the requested access rights in software. However, as the current
>> implementation
>> of p2m_mem_access_check_and_get_page makes use of the hardware-aided gva to
>> ipa
>> translation, the translation might also fail because of reasons stated above
>> and will become equally relevant for the altp2m implementation on ARM. As
>> such, we provide a software guest translation table walk to address the above
>> mentioned issue.
>>
>> The current version of the implementation supports translation of both the
>> short-descriptor as well as the long-descriptor translation table format on
>> ARMv7 and ARMv8 (AArch32/AArch64).
>>
>> This revised version incorporates the comments of the previous patch series.
>> In
>> this patch version we refine the definition of PAGE_SIZE_GRAN and
>> PAGE_MASK_GRAN. In particular, we use PAGE_SIZE_GRAN to define PAGE_MASK_GRAN
>> and thus avoid these defines to have a differing type. We also changed the
>> previously introduced macro BITS_PER_LONG_LONG to BITS_PER_LLONG. Further
>> changes comprise minor adjustments in comments and renaming of macros and
>> function parameters. Some additional changes comprising code readability and
>> correct type usage have been made and stated in the individual commits.
>>
>> The following patch series can be found on Github[0].
>
> I tried this series today with the change [1] in Xen to check the translation
> is valid. However, I got a failure when booting non-LPAE arm32 Dom0:
>
That's odd.. Thanks for the information. I will investigate this issue
next week, as soon as I have access to our ARMv7 board.
> (XEN) Loading kernel from boot module @ 0000000080008000
> (XEN) Allocating 1:1 mappings totalling 512MB for dom0:
> (XEN) BANK[0] 0x000000a0000000-0x000000c0000000 (512MB)
> (XEN) Grant table range: 0x000000ffe00000-0x000000ffe6a000
> (XEN) Loading zImage from 0000000080008000 to
> 00000000a7800000-00000000a7f50e28
> (XEN) Allocating PPI 16 for event channel interrupt
> (XEN) Loading dom0 DTB to 0x00000000a8000000-0x00000000a8001f8e
> (XEN) Std. Loglevel: All
> (XEN) Guest Loglevel: All
> (XEN) guest_walk_tables: gva 0xffeff018 pipa 0x1c090018
> (XEN) access_guest_memory_by_ipa: gpa 0xa0207ff8
> (XEN) access_guest_memory_by_ipa: gpa 0xffffffffa13aebfc
> (XEN) d0: guestcopy: failed to get table entry.
> (XEN) Xen BUG at traps.c:2737
> (XEN) ----[ Xen-4.10-unstable arm32 debug=y Not tainted ]----
> (XEN) CPU: 0
> (XEN) PC: 00264dc0 do_trap_guest_sync+0x161c/0x1804
> (XEN) CPSR: a000005a MODE:Hypervisor
> (XEN) R0: ffffffea R1: 00000000 R2: 00000000 R3: 0000004a
> (XEN) R4: 93830007 R5: 47fcff58 R6: 93830007 R7: 00000007
> (XEN) R8: 1c090000 R9: 00000000 R10:00000000 R11:47fcff54 R12:ffffffea
> (XEN) HYP: SP: 47fcfee4 LR: 00258dec
> (XEN)
> (XEN) VTCR_EL2: 80003558
> (XEN) VTTBR_EL2: 00010008f3ffc000
> (XEN)
> (XEN) SCTLR_EL2: 30cd187f
> (XEN) HCR_EL2: 000000000038663f
> (XEN) TTBR0_EL2: 00000000fff02000
> (XEN)
> (XEN) ESR_EL2: 00000000
> (XEN) HPFAR_EL2: 00000000001c0900
> (XEN) HDFAR: ffeff018
> (XEN) HIFAR: 00000000
> (XEN)
> (XEN) Xen stack trace from sp=47fcfee4:
> (XEN) 00000000 47fcff34 00256008 47fcfefc 47fcfefc 200000da 00000004
> 47fd48f4
> (XEN) 002d5ef0 00000004 002d1f00 00000004 00000000 002d1f00 c163f740
> 93830007
> (XEN) ffeff018 1c090018 00000000 47fcff44 c15e70ac 0000005b c15e70ac
> c074400c
> (XEN) 00000031 00000000 c0743ff8 47fcff58 00268ce0 c15e70ac 0000005b
> 00000031
> (XEN) ffeff000 c15e70ac 0000005b c15e70ac c074400c 00000031 00000000
> c0743ff8
> (XEN) 00000000 0000001f ffffffff 00000000 c074401c 200001d3 93830007
> 00000000
> (XEN) c161cac0 c161cac0 c1501de0 c0735640 c161cacc c161cacc c161cad8
> c161cad8
> (XEN) 00000000 00000000 00000000 00000000 00000000 c161cae4 c161cae4
> 400001d3
> (XEN) 00000000 00000000 00000000 00000000 00000000 dfdfdfcf cfdfdfdf
> (XEN) Xen call trace:
> (XEN) [<00264dc0>] do_trap_guest_sync+0x161c/0x1804 (PC)
> (XEN) [<00258dec>] access_guest_memory_by_ipa+0x25c/0x284 (LR)
> (XEN) [<00268ce0>] entry.o#return_from_trap+0/0x4
> (XEN)
> (XEN)
> (XEN) ****************************************
> (XEN) Panic on CPU 0:
> (XEN) Xen BUG at traps.c:2737
> (XEN) ****************************************
> (XEN)
> (XEN) Reboot in five seconds...
>
> The IPA 0xffffffffa13aebfc is not valid for the domain.
>
> Cheers,
>
> [1]
> diff --git a/xen/arch/arm/guestcopy.c b/xen/arch/arm/guestcopy.c
> index 4ee07fcea3..89c5ebf3cf 100644
> --- a/xen/arch/arm/guestcopy.c
> +++ b/xen/arch/arm/guestcopy.c
> @@ -139,6 +139,8 @@ int access_guest_memory_by_ipa(struct domain *d, paddr_t
> gpa, void *buf,
> return -EINVAL;
> }
>
> + printk("%s: gpa 0x%llx\n", __FUNCTION__, gpa);
> +
> page = get_page_from_gfn(d, paddr_to_pfn(gpa), &p2mt, P2M_ALLOC);
> if ( !page )
> {
> diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
> index c07999b518..904abafcae 100644
> --- a/xen/arch/arm/traps.c
> +++ b/xen/arch/arm/traps.c
> @@ -2688,6 +2688,8 @@ static bool try_map_mmio(gfn_t gfn)
> return !map_regions_p2mt(d, gfn, 1, mfn, p2m_mmio_direct_c);
> }
>
> +#include <asm/guest_walk.h>
> +
> static void do_trap_data_abort_guest(struct cpu_user_regs *regs,
> const union hsr hsr)
> {
> @@ -2725,6 +2727,17 @@ static void do_trap_data_abort_guest(struct
> cpu_user_regs *regs,
> return; /* Try again */
> }
>
> + {
> + paddr_t ipa, pipa;
> + rc = gva_to_ipa(info.gva, &info.ipa, GV2M_READ);
> + BUG_ON(rc);
> + printk("guest_walk_tables: gva 0x%x pipa 0x%llx\n",
> + info.gva, pipa);
> + rc = guest_walk_tables(current, info.gva, &ipa, NULL);
> + BUG_ON(rc);
> + BUG_ON(ipa != pipa);
> + }
> +
> switch ( fsc )
> {
> case FSC_FLT_PERM:
>
>>
>> Cheers,
>> ~Sergej
>>
>> [0] https://github.com/sergej-proskurin/xen (branch arm-gpt-walk-v7)
>>
>> Sergej Proskurin (14):
>> arm/mem_access: Add and cleanup (TCR_|TTBCR_)* defines
>> arm/mem_access: Move PAGE_*_* macros to xen/page-defs.h
>> arm/mem_access: Add defines supporting PTs with varying page sizes
>> arm/lpae: Introduce lpae_is_page helper
>> arm/mem_access: Add short-descriptor pte typedefs and macros
>> arm/mem_access: Introduce GV2M_EXEC permission
>> arm/mem_access: Introduce BIT_ULL bit operation
>> arm/mem_access: Introduce GENMASK_ULL bit operation
>> arm/guest_access: Move vgic_access_guest_memory to guest_access.h
>> arm/guest_access: Rename vgic_access_guest_memory
>> arm/mem_access: Add software guest-page-table walk
>> arm/mem_access: Add long-descriptor based gpt
>> arm/mem_access: Add short-descriptor based gpt
>> arm/mem_access: Walk the guest's pt in software
>>
>> xen/arch/arm/Makefile | 1 +
>> xen/arch/arm/guest_walk.c | 631
>> +++++++++++++++++++++++++++++++++++++
>> xen/arch/arm/guestcopy.c | 50 +++
>> xen/arch/arm/mem_access.c | 31 +-
>> xen/arch/arm/vgic-v3-its.c | 37 +--
>> xen/arch/arm/vgic.c | 49 ---
>> xen/include/asm-arm/bitops.h | 1 +
>> xen/include/asm-arm/config.h | 2 +
>> xen/include/asm-arm/guest_access.h | 3 +
>> xen/include/asm-arm/guest_walk.h | 19 ++
>> xen/include/asm-arm/lpae.h | 66 ++++
>> xen/include/asm-arm/page.h | 1 +
>> xen/include/asm-arm/processor.h | 69 +++-
>> xen/include/asm-arm/short-desc.h | 130 ++++++++
>> xen/include/asm-arm/vgic.h | 3 -
>> xen/include/asm-x86/config.h | 2 +
>> xen/include/xen/bitops.h | 3 +
>> xen/include/xen/iommu.h | 15 +-
>> xen/include/xen/page-defs.h | 24 ++
>> 19 files changed, 1048 insertions(+), 89 deletions(-)
>> create mode 100644 xen/arch/arm/guest_walk.c
>> create mode 100644 xen/include/asm-arm/guest_walk.h
>> create mode 100644 xen/include/asm-arm/short-desc.h
>> create mode 100644 xen/include/xen/page-defs.h
>>
Cheers,
~Sergej
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