Add KVM selftests header files for LoongArch, including processor.h
and kvm_util_base.h. Those mainly contain LoongArch CSR register defines
and page table information. And change DEFAULT_GUEST_TEST_MEM base addr
for LoongArch.
Signed-off-by: Tianrui Zhao <[email protected]>
---
.../selftests/kvm/include/kvm_util_base.h | 5 +
.../kvm/include/loongarch/processor.h | 133 ++++++++++++++++++
.../testing/selftests/kvm/include/memstress.h | 2 +
3 files changed, 140 insertions(+)
create mode 100644 tools/testing/selftests/kvm/include/loongarch/processor.h
diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index a18db6a7b3c..97f8b24741b 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -218,6 +218,11 @@ extern enum vm_guest_mode vm_mode_default;
#define MIN_PAGE_SHIFT 12U
#define ptes_per_page(page_size) ((page_size) / 8)
+#elif defined(__loongarch__)
+#define VM_MODE_DEFAULT VM_MODE_P36V47_16K
+#define MIN_PAGE_SHIFT 14U
+#define ptes_per_page(page_size) ((page_size) / 8)
+
#endif
#define MIN_PAGE_SIZE (1U << MIN_PAGE_SHIFT)
diff --git a/tools/testing/selftests/kvm/include/loongarch/processor.h b/tools/testing/selftests/kvm/include/loongarch/processor.h
new file mode 100644
index 00000000000..cea6b284131
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/loongarch/processor.h
@@ -0,0 +1,133 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef SELFTEST_KVM_PROCESSOR_H
+#define SELFTEST_KVM_PROCESSOR_H
+
+#define _PAGE_VALID_SHIFT 0
+#define _PAGE_DIRTY_SHIFT 1
+#define _PAGE_PLV_SHIFT 2 /* 2~3, two bits */
+#define _CACHE_SHIFT 4 /* 4~5, two bits */
+#define _PAGE_PRESENT_SHIFT 7
+#define _PAGE_WRITE_SHIFT 8
+
+#define PLV_KERN 0
+#define PLV_USER 3
+#define PLV_MASK 0x3
+
+#define _PAGE_VALID (0x1UL << _PAGE_VALID_SHIFT)
+#define _PAGE_PRESENT (0x1UL << _PAGE_PRESENT_SHIFT)
+#define _PAGE_WRITE (0x1UL << _PAGE_WRITE_SHIFT)
+#define _PAGE_DIRTY (0x1UL << _PAGE_DIRTY_SHIFT)
+#define _PAGE_USER (PLV_USER << _PAGE_PLV_SHIFT)
+#define __READABLE (_PAGE_VALID)
+#define __WRITEABLE (_PAGE_DIRTY | _PAGE_WRITE)
+#define _CACHE_CC (0x1UL << _CACHE_SHIFT) /* Coherent Cached */
+
+/* general registers */
+#define zero $r0
+#define ra $r1
+#define tp $r2
+#define sp $r3
+#define a0 $r4
+#define a1 $r5
+#define a2 $r6
+#define a3 $r7
+#define a4 $r8
+#define a5 $r9
+#define a6 $r10
+#define a7 $r11
+#define t0 $r12
+#define t1 $r13
+#define t2 $r14
+#define t3 $r15
+#define t4 $r16
+#define t5 $r17
+#define t6 $r18
+#define t7 $r19
+#define t8 $r20
+#define u0 $r21
+#define fp $r22
+#define s0 $r23
+#define s1 $r24
+#define s2 $r25
+#define s3 $r26
+#define s4 $r27
+#define s5 $r28
+#define s6 $r29
+#define s7 $r30
+#define s8 $r31
+
+#define PS_4K 0x0000000c
+#define PS_8K 0x0000000d
+#define PS_16K 0x0000000e
+#define PS_DEFAULT_SIZE PS_16K
+
+/* Basic CSR registers */
+#define LOONGARCH_CSR_CRMD 0x0 /* Current mode info */
+#define CSR_CRMD_PG_SHIFT 4
+#define CSR_CRMD_PG (0x1UL << CSR_CRMD_PG_SHIFT)
+#define CSR_CRMD_IE_SHIFT 2
+#define CSR_CRMD_IE (0x1UL << CSR_CRMD_IE_SHIFT)
+#define CSR_CRMD_PLV_SHIFT 0
+#define CSR_CRMD_PLV_WIDTH 2
+#define CSR_CRMD_PLV (0x3UL << CSR_CRMD_PLV_SHIFT)
+#define PLV_MASK 0x3
+
+#define LOONGARCH_CSR_PRMD 0x1
+#define LOONGARCH_CSR_EUEN 0x2
+#define LOONGARCH_CSR_ECFG 0x4
+#define LOONGARCH_CSR_ESTAT 0x5 /* Exception status */
+#define LOONGARCH_CSR_ERA 0x6 /* ERA */
+#define LOONGARCH_CSR_BADV 0x7 /* Bad virtual address */
+#define LOONGARCH_CSR_EENTRY 0xc
+#define LOONGARCH_CSR_TLBIDX 0x10 /* TLB Index, EHINV, PageSize, NP */
+#define CSR_TLBIDX_PS_SHIFT 24
+#define CSR_TLBIDX_PS_WIDTH 6
+#define CSR_TLBIDX_PS (0x3fUL << CSR_TLBIDX_PS_SHIFT)
+#define CSR_TLBIDX_SIZEM 0x3f000000
+#define CSR_TLBIDX_SIZE CSR_TLBIDX_PS_SHIFT
+
+#define LOONGARCH_CSR_ASID 0x18 /* ASID */
+/* Page table base address when VA[VALEN-1] = 0 */
+#define LOONGARCH_CSR_PGDL 0x19
+/* Page table base address when VA[VALEN-1] = 1 */
+#define LOONGARCH_CSR_PGDH 0x1a
+/* Page table base */
+#define LOONGARCH_CSR_PGD 0x1b
+#define LOONGARCH_CSR_PWCTL0 0x1c
+#define LOONGARCH_CSR_PWCTL1 0x1d
+#define LOONGARCH_CSR_STLBPGSIZE 0x1e
+#define LOONGARCH_CSR_CPUID 0x20
+#define LOONGARCH_CSR_KS0 0x30
+#define LOONGARCH_CSR_KS1 0x31
+#define LOONGARCH_CSR_TMID 0x40
+#define LOONGARCH_CSR_TCFG 0x41
+#define LOONGARCH_CSR_TLBRENTRY 0x88 /* TLB refill exception entry */
+/* KSave for TLB refill exception */
+#define LOONGARCH_CSR_TLBRSAVE 0x8b
+#define LOONGARCH_CSR_TLBREHI 0x8e
+#define CSR_TLBREHI_PS_SHIFT 0
+#define CSR_TLBREHI_PS (0x3fUL << CSR_TLBREHI_PS_SHIFT)
+
+#define DEFAULT_LOONARCH64_STACK_MIN 0x4000
+#define DEFAULT_LOONARCH64_PAGE_TABLE_MIN 0x4000
+#define EXREGS_GPRS (32)
+
+#ifndef __ASSEMBLER__
+struct ex_regs {
+ unsigned long regs[EXREGS_GPRS];
+ unsigned long pc;
+ unsigned long estat;
+ unsigned long badv;
+};
+
+extern void handle_tlb_refill(void);
+extern void handle_exception(void);
+#endif
+
+#define PC_OFFSET_EXREGS ((EXREGS_GPRS + 0) * 8)
+#define ESTAT_OFFSET_EXREGS ((EXREGS_GPRS + 1) * 8)
+#define BADV_OFFSET_EXREGS ((EXREGS_GPRS + 2) * 8)
+#define EXREGS_SIZE ((EXREGS_GPRS + 3) * 8)
+
+#endif /* SELFTEST_KVM_PROCESSOR_H */
diff --git a/tools/testing/selftests/kvm/include/memstress.h b/tools/testing/selftests/kvm/include/memstress.h
index ce4e603050e..5bcdaf2efab 100644
--- a/tools/testing/selftests/kvm/include/memstress.h
+++ b/tools/testing/selftests/kvm/include/memstress.h
@@ -13,7 +13,9 @@
#include "kvm_util.h"
/* Default guest test virtual memory offset */
+#ifndef DEFAULT_GUEST_TEST_MEM
#define DEFAULT_GUEST_TEST_MEM 0xc0000000
+#endif
#define DEFAULT_PER_VCPU_MEM_SIZE (1 << 30) /* 1G */
--
2.39.1
Hi, Sean:
I want to change the definition of DEFAULT_GUEST_TEST_MEM in the common
file "memstress.h", like this:
/* Default guest test virtual memory offset */
+#ifndef DEFAULT_GUEST_TEST_MEM
#define DEFAULT_GUEST_TEST_MEM 0xc0000000
+#endif
As this address should be re-defined in LoongArch headers.
So, do you have any suggesstion?
Thanks
Tianrui Zhao
在 2023/11/30 下午7:18, Tianrui Zhao 写道:
> Add KVM selftests header files for LoongArch, including processor.h
> and kvm_util_base.h. Those mainly contain LoongArch CSR register defines
> and page table information. And change DEFAULT_GUEST_TEST_MEM base addr
> for LoongArch.
>
> Signed-off-by: Tianrui Zhao <[email protected]>
> ---
> .../selftests/kvm/include/kvm_util_base.h | 5 +
> .../kvm/include/loongarch/processor.h | 133 ++++++++++++++++++
> .../testing/selftests/kvm/include/memstress.h | 2 +
> 3 files changed, 140 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/include/loongarch/processor.h
>
> diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
> index a18db6a7b3c..97f8b24741b 100644
> --- a/tools/testing/selftests/kvm/include/kvm_util_base.h
> +++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
> @@ -218,6 +218,11 @@ extern enum vm_guest_mode vm_mode_default;
> #define MIN_PAGE_SHIFT 12U
> #define ptes_per_page(page_size) ((page_size) / 8)
>
> +#elif defined(__loongarch__)
> +#define VM_MODE_DEFAULT VM_MODE_P36V47_16K
> +#define MIN_PAGE_SHIFT 14U
> +#define ptes_per_page(page_size) ((page_size) / 8)
> +
> #endif
>
> #define MIN_PAGE_SIZE (1U << MIN_PAGE_SHIFT)
> diff --git a/tools/testing/selftests/kvm/include/loongarch/processor.h b/tools/testing/selftests/kvm/include/loongarch/processor.h
> new file mode 100644
> index 00000000000..cea6b284131
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/loongarch/processor.h
> @@ -0,0 +1,133 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +
> +#ifndef SELFTEST_KVM_PROCESSOR_H
> +#define SELFTEST_KVM_PROCESSOR_H
> +
> +#define _PAGE_VALID_SHIFT 0
> +#define _PAGE_DIRTY_SHIFT 1
> +#define _PAGE_PLV_SHIFT 2 /* 2~3, two bits */
> +#define _CACHE_SHIFT 4 /* 4~5, two bits */
> +#define _PAGE_PRESENT_SHIFT 7
> +#define _PAGE_WRITE_SHIFT 8
> +
> +#define PLV_KERN 0
> +#define PLV_USER 3
> +#define PLV_MASK 0x3
> +
> +#define _PAGE_VALID (0x1UL << _PAGE_VALID_SHIFT)
> +#define _PAGE_PRESENT (0x1UL << _PAGE_PRESENT_SHIFT)
> +#define _PAGE_WRITE (0x1UL << _PAGE_WRITE_SHIFT)
> +#define _PAGE_DIRTY (0x1UL << _PAGE_DIRTY_SHIFT)
> +#define _PAGE_USER (PLV_USER << _PAGE_PLV_SHIFT)
> +#define __READABLE (_PAGE_VALID)
> +#define __WRITEABLE (_PAGE_DIRTY | _PAGE_WRITE)
> +#define _CACHE_CC (0x1UL << _CACHE_SHIFT) /* Coherent Cached */
> +
> +/* general registers */
> +#define zero $r0
> +#define ra $r1
> +#define tp $r2
> +#define sp $r3
> +#define a0 $r4
> +#define a1 $r5
> +#define a2 $r6
> +#define a3 $r7
> +#define a4 $r8
> +#define a5 $r9
> +#define a6 $r10
> +#define a7 $r11
> +#define t0 $r12
> +#define t1 $r13
> +#define t2 $r14
> +#define t3 $r15
> +#define t4 $r16
> +#define t5 $r17
> +#define t6 $r18
> +#define t7 $r19
> +#define t8 $r20
> +#define u0 $r21
> +#define fp $r22
> +#define s0 $r23
> +#define s1 $r24
> +#define s2 $r25
> +#define s3 $r26
> +#define s4 $r27
> +#define s5 $r28
> +#define s6 $r29
> +#define s7 $r30
> +#define s8 $r31
> +
> +#define PS_4K 0x0000000c
> +#define PS_8K 0x0000000d
> +#define PS_16K 0x0000000e
> +#define PS_DEFAULT_SIZE PS_16K
> +
> +/* Basic CSR registers */
> +#define LOONGARCH_CSR_CRMD 0x0 /* Current mode info */
> +#define CSR_CRMD_PG_SHIFT 4
> +#define CSR_CRMD_PG (0x1UL << CSR_CRMD_PG_SHIFT)
> +#define CSR_CRMD_IE_SHIFT 2
> +#define CSR_CRMD_IE (0x1UL << CSR_CRMD_IE_SHIFT)
> +#define CSR_CRMD_PLV_SHIFT 0
> +#define CSR_CRMD_PLV_WIDTH 2
> +#define CSR_CRMD_PLV (0x3UL << CSR_CRMD_PLV_SHIFT)
> +#define PLV_MASK 0x3
> +
> +#define LOONGARCH_CSR_PRMD 0x1
> +#define LOONGARCH_CSR_EUEN 0x2
> +#define LOONGARCH_CSR_ECFG 0x4
> +#define LOONGARCH_CSR_ESTAT 0x5 /* Exception status */
> +#define LOONGARCH_CSR_ERA 0x6 /* ERA */
> +#define LOONGARCH_CSR_BADV 0x7 /* Bad virtual address */
> +#define LOONGARCH_CSR_EENTRY 0xc
> +#define LOONGARCH_CSR_TLBIDX 0x10 /* TLB Index, EHINV, PageSize, NP */
> +#define CSR_TLBIDX_PS_SHIFT 24
> +#define CSR_TLBIDX_PS_WIDTH 6
> +#define CSR_TLBIDX_PS (0x3fUL << CSR_TLBIDX_PS_SHIFT)
> +#define CSR_TLBIDX_SIZEM 0x3f000000
> +#define CSR_TLBIDX_SIZE CSR_TLBIDX_PS_SHIFT
> +
> +#define LOONGARCH_CSR_ASID 0x18 /* ASID */
> +/* Page table base address when VA[VALEN-1] = 0 */
> +#define LOONGARCH_CSR_PGDL 0x19
> +/* Page table base address when VA[VALEN-1] = 1 */
> +#define LOONGARCH_CSR_PGDH 0x1a
> +/* Page table base */
> +#define LOONGARCH_CSR_PGD 0x1b
> +#define LOONGARCH_CSR_PWCTL0 0x1c
> +#define LOONGARCH_CSR_PWCTL1 0x1d
> +#define LOONGARCH_CSR_STLBPGSIZE 0x1e
> +#define LOONGARCH_CSR_CPUID 0x20
> +#define LOONGARCH_CSR_KS0 0x30
> +#define LOONGARCH_CSR_KS1 0x31
> +#define LOONGARCH_CSR_TMID 0x40
> +#define LOONGARCH_CSR_TCFG 0x41
> +#define LOONGARCH_CSR_TLBRENTRY 0x88 /* TLB refill exception entry */
> +/* KSave for TLB refill exception */
> +#define LOONGARCH_CSR_TLBRSAVE 0x8b
> +#define LOONGARCH_CSR_TLBREHI 0x8e
> +#define CSR_TLBREHI_PS_SHIFT 0
> +#define CSR_TLBREHI_PS (0x3fUL << CSR_TLBREHI_PS_SHIFT)
> +
> +#define DEFAULT_LOONARCH64_STACK_MIN 0x4000
> +#define DEFAULT_LOONARCH64_PAGE_TABLE_MIN 0x4000
> +#define EXREGS_GPRS (32)
> +
> +#ifndef __ASSEMBLER__
> +struct ex_regs {
> + unsigned long regs[EXREGS_GPRS];
> + unsigned long pc;
> + unsigned long estat;
> + unsigned long badv;
> +};
> +
> +extern void handle_tlb_refill(void);
> +extern void handle_exception(void);
> +#endif
> +
> +#define PC_OFFSET_EXREGS ((EXREGS_GPRS + 0) * 8)
> +#define ESTAT_OFFSET_EXREGS ((EXREGS_GPRS + 1) * 8)
> +#define BADV_OFFSET_EXREGS ((EXREGS_GPRS + 2) * 8)
> +#define EXREGS_SIZE ((EXREGS_GPRS + 3) * 8)
> +
> +#endif /* SELFTEST_KVM_PROCESSOR_H */
> diff --git a/tools/testing/selftests/kvm/include/memstress.h b/tools/testing/selftests/kvm/include/memstress.h
> index ce4e603050e..5bcdaf2efab 100644
> --- a/tools/testing/selftests/kvm/include/memstress.h
> +++ b/tools/testing/selftests/kvm/include/memstress.h
> @@ -13,7 +13,9 @@
> #include "kvm_util.h"
>
> /* Default guest test virtual memory offset */
> +#ifndef DEFAULT_GUEST_TEST_MEM
> #define DEFAULT_GUEST_TEST_MEM 0xc0000000
> +#endif
>
> #define DEFAULT_PER_VCPU_MEM_SIZE (1 << 30) /* 1G */
>
On Tue, Dec 12, 2023, zhaotianrui wrote:
> Hi, Sean:
>
> I want to change the definition of DEFAULT_GUEST_TEST_MEM in the common
> file "memstress.h", like this:
>
> /* Default guest test virtual memory offset */
> +#ifndef DEFAULT_GUEST_TEST_MEM
> #define DEFAULT_GUEST_TEST_MEM 0xc0000000
> +#endif
>
> As this address should be re-defined in LoongArch headers.
Why? E.g. is 0xc0000000 unconditionally reserved, not guaranteed to be valid,
something else?
> So, do you have any suggesstion?
Hmm, I think ideally kvm_util_base.h would define a range of memory that can be
used by tests for arbitrary data. Multiple tests use 0xc0000000, which is not
entirely arbitrary, i.e. it doesn't _need_ to be 0xc0000000, but 0xc0000000 is
convenient because it's 32-bit addressable and doesn't overlap reserved areas in
other architectures.
在 2023/12/13 上午1:18, Sean Christopherson 写道:
> On Tue, Dec 12, 2023, zhaotianrui wrote:
>> Hi, Sean:
>>
>> I want to change the definition of DEFAULT_GUEST_TEST_MEM in the common
>> file "memstress.h", like this:
>>
>> /* Default guest test virtual memory offset */
>> +#ifndef DEFAULT_GUEST_TEST_MEM
>> #define DEFAULT_GUEST_TEST_MEM 0xc0000000
>> +#endif
>>
>> As this address should be re-defined in LoongArch headers.
>
> Why? E.g. is 0xc0000000 unconditionally reserved, not guaranteed to be valid,
> something else?
>
>> So, do you have any suggesstion?
>
> Hmm, I think ideally kvm_util_base.h would define a range of memory that can be
> used by tests for arbitrary data. Multiple tests use 0xc0000000, which is not
> entirely arbitrary, i.e. it doesn't _need_ to be 0xc0000000, but 0xc0000000 is
> convenient because it's 32-bit addressable and doesn't overlap reserved areas in
> other architectures.
>
Thanks for your explanation, and LoongArch want to define
DEFAULT_GUEST_TEST_MEM to 0x130000000. As default base address for
application loading is 0x120000000, DEFAULT_GUEST_TEST_MEM should be
larger than app loading address, so that PER_VCPU_MEM_SIZE can be large
enough, and kvm selftests app size is smaller than 256M in generic.
Thanks
Tianrui Zhao
On 2023/12/13 下午3:15, zhaotianrui wrote:
>
>
> 在 2023/12/13 上午1:18, Sean Christopherson 写道:
>> On Tue, Dec 12, 2023, zhaotianrui wrote:
>>> Hi, Sean:
>>>
>>> I want to change the definition of DEFAULT_GUEST_TEST_MEM in the common
>>> file "memstress.h", like this:
>>>
>>> /* Default guest test virtual memory offset */
>>> +#ifndef DEFAULT_GUEST_TEST_MEM
>>> #define DEFAULT_GUEST_TEST_MEM 0xc0000000
>>> +#endif
>>>
>>> As this address should be re-defined in LoongArch headers.
>>
>> Why? E.g. is 0xc0000000 unconditionally reserved, not guaranteed to
>> be valid,
>> something else?
>>
>>> So, do you have any suggesstion?
>>
>> Hmm, I think ideally kvm_util_base.h would define a range of memory
>> that can be
>> used by tests for arbitrary data. Multiple tests use 0xc0000000,
>> which is not
>> entirely arbitrary, i.e. it doesn't _need_ to be 0xc0000000, but
>> 0xc0000000 is
>> convenient because it's 32-bit addressable and doesn't overlap
>> reserved areas in
>> other architectures.
In general text entry address of user application on x86/arm64 Linux
is 0x200000, however on LoongArch system text entry address is strange,
its value 0x120000000.
When DEFAULT_GUEST_TEST_MEM is defined as 0xc0000000, there is
limitation for guest memory size, it cannot exceed 0x120000000 -
0xc000000 = 1.5G bytes, else there will be conflict. However
there is no such issue on x86/arm64, since 0xc0000000 is above text
entry address 0x200000.
The LoongArch link scripts actually is strange, it brings out some
compatible issues such dpdk/kvm selftest when user applications
want fixed virtual address space.
So here DEFAULT_GUEST_TEST_MEM is defined as 0x130000000 separately,
maybe 0x140000000 is better since it is 1G super-page aligned for 4K
page size.
Regards
Bibo Mao
>>
> Thanks for your explanation, and LoongArch want to define
> DEFAULT_GUEST_TEST_MEM to 0x130000000. As default base address for
> application loading is 0x120000000, DEFAULT_GUEST_TEST_MEM should be
> larger than app loading address, so that PER_VCPU_MEM_SIZE can be large
> enough, and kvm selftests app size is smaller than 256M in generic.
>
> Thanks
> Tianrui Zhao
On Wed, Dec 13, 2023, maobibo wrote:
>
> On 2023/12/13 下午3:15, zhaotianrui wrote:
> >
> > 在 2023/12/13 上午1:18, Sean Christopherson 写道:
> > > On Tue, Dec 12, 2023, zhaotianrui wrote:
> > > > Hi, Sean:
> > > >
> > > > I want to change the definition of DEFAULT_GUEST_TEST_MEM in the common
> > > > file "memstress.h", like this:
> > > >
> > > > /* Default guest test virtual memory offset */
> > > > +#ifndef DEFAULT_GUEST_TEST_MEM
> > > > #define DEFAULT_GUEST_TEST_MEM 0xc0000000
> > > > +#endif
> > > >
> > > > As this address should be re-defined in LoongArch headers.
> > >
> > > Why? E.g. is 0xc0000000 unconditionally reserved, not guaranteed to
> > > be valid,
> > > something else?
> > >
> > > > So, do you have any suggesstion?
> > >
> > > Hmm, I think ideally kvm_util_base.h would define a range of memory that
> > > can be used by tests for arbitrary data. Multiple tests use 0xc0000000,
> > > which is not entirely arbitrary, i.e. it doesn't _need_ to be 0xc0000000,
> > > but 0xc0000000 is convenient because it's 32-bit addressable and doesn't
> > > overlap reserved areas in other architectures.
> In general text entry address of user application on x86/arm64 Linux
> is 0x200000, however on LoongArch system text entry address is strange, its
> value 0x120000000.
>
> When DEFAULT_GUEST_TEST_MEM is defined as 0xc0000000, there is limitation
> for guest memory size, it cannot exceed 0x120000000 - 0xc000000 = 1.5G
> bytes, else there will be conflict. However there is no such issue on
> x86/arm64, since 0xc0000000 is above text entry address 0x200000.
Ugh, I spent a good 30 minutes trying to figure out how any of this works on x86
before I realized DEFAULT_GUEST_TEST_MEM is used for the guest _virtual_ address
space.
I was thinking we were talking about guest _physical_ address, hence my comments
about it being 32-bit addressable and not overlappin reserved areas. E.g. on x86,
anything remotely resembling a real system has regular memory, a.k.a. DRAM, split
between low memory (below the 32-bit boundary, i.e. below 4GiB) and high memory
(from 4GiB to the max legal physical address). Addresses above "top of lower
usable DRAM" (TOLUD) are reserved (again, in a "real" system) for things like
PCI, local APIC, I/O APIC, and the _architecturally_ defined RESET vector.
I couldn't figure out how x86 worked, because KVM creates an KVM-internal memslot
at address 0xfee00000. And then I realized the test creates memslots at completely
different GPAs, and DEFAULT_GUEST_TEST_MEM is used only as super arbitrary
guest virtual address.
*sigh*
Anyways...
> The LoongArch link scripts actually is strange, it brings out some
> compatible issues such dpdk/kvm selftest when user applications
> want fixed virtual address space.
Can you elaborate on compatiblity issues? I don't see the connection between
DPDK and KVM selftests.
> So here DEFAULT_GUEST_TEST_MEM is defined as 0x130000000 separately, maybe
> 0x140000000 is better since it is 1G super-page aligned for 4K page size.
I would strongly prefer we carve out a virtual address range that *all* tests
can safely use for test-specific code and data. E.g. if/when we add userspace
support to selftests, I like the idea of having dedicated address spaces for
kernel vs. user[*].
Maybe we can march in that generally direction and define test's virtual address
range to be in kernel space, i.e. the high half. I assume/hope that would play
nice with all architectures' entry points?
[*] https://lore.kernel.org/all/[email protected]
On 2023/12/14 上午7:56, Sean Christopherson wrote:
> On Wed, Dec 13, 2023, maobibo wrote:
>>
>> On 2023/12/13 下午3:15, zhaotianrui wrote:
>>>
>>> 在 2023/12/13 上午1:18, Sean Christopherson 写道:
>>>> On Tue, Dec 12, 2023, zhaotianrui wrote:
>>>>> Hi, Sean:
>>>>>
>>>>> I want to change the definition of DEFAULT_GUEST_TEST_MEM in the common
>>>>> file "memstress.h", like this:
>>>>>
>>>>> /* Default guest test virtual memory offset */
>>>>> +#ifndef DEFAULT_GUEST_TEST_MEM
>>>>> #define DEFAULT_GUEST_TEST_MEM 0xc0000000
>>>>> +#endif
>>>>>
>>>>> As this address should be re-defined in LoongArch headers.
>>>>
>>>> Why? E.g. is 0xc0000000 unconditionally reserved, not guaranteed to
>>>> be valid,
>>>> something else?
>>>>
>>>>> So, do you have any suggesstion?
>>>>
>>>> Hmm, I think ideally kvm_util_base.h would define a range of memory that
>>>> can be used by tests for arbitrary data. Multiple tests use 0xc0000000,
>>>> which is not entirely arbitrary, i.e. it doesn't _need_ to be 0xc0000000,
>>>> but 0xc0000000 is convenient because it's 32-bit addressable and doesn't
>>>> overlap reserved areas in other architectures.
>> In general text entry address of user application on x86/arm64 Linux
>> is 0x200000, however on LoongArch system text entry address is strange, its
>> value 0x120000000.
>>
>> When DEFAULT_GUEST_TEST_MEM is defined as 0xc0000000, there is limitation
>> for guest memory size, it cannot exceed 0x120000000 - 0xc000000 = 1.5G
>> bytes, else there will be conflict. However there is no such issue on
>> x86/arm64, since 0xc0000000 is above text entry address 0x200000.
>
> Ugh, I spent a good 30 minutes trying to figure out how any of this works on x86
> before I realized DEFAULT_GUEST_TEST_MEM is used for the guest _virtual_ address
> space.
>
> I was thinking we were talking about guest _physical_ address, hence my comments
> about it being 32-bit addressable and not overlappin reserved areas. E.g. on x86,
> anything remotely resembling a real system has regular memory, a.k.a. DRAM, split
> between low memory (below the 32-bit boundary, i.e. below 4GiB) and high memory
> (from 4GiB to the max legal physical address). Addresses above "top of lower
> usable DRAM" (TOLUD) are reserved (again, in a "real" system) for things like
> PCI, local APIC, I/O APIC, and the _architecturally_ defined RESET vector.
>
> I couldn't figure out how x86 worked, because KVM creates an KVM-internal memslot
> at address 0xfee00000. And then I realized the test creates memslots at completely
> different GPAs, and DEFAULT_GUEST_TEST_MEM is used only as super arbitrary
> guest virtual address.
The framework and idea of kvm selftest is very good and intrinsic, and
it is very easy to write unit test case for kvm -:)
>
> *sigh*
>
> Anyways...
>
>> The LoongArch link scripts actually is strange, it brings out some
>> compatible issues such dpdk/kvm selftest when user applications
>> want fixed virtual address space.
>
> Can you elaborate on compatiblity issues? I don't see the connection between
> DPDK and KVM selftests.
No, there is no the connection between DPDK and KVM selftests. I mean
that some applications which use fixed VA address have the same issue,
however this kind of usage is OK on X86/ARM. DPDK also uses fixed IOVA
address(0xC0000000) when it is combined with IOMMU, there is the similar
conflict issue on LoongArch machines.
>
>> So here DEFAULT_GUEST_TEST_MEM is defined as 0x130000000 separately, maybe
>> 0x140000000 is better since it is 1G super-page aligned for 4K page size.
>
> I would strongly prefer we carve out a virtual address range that *all* tests
> can safely use for test-specific code and data. E.g. if/when we add userspace
> support to selftests, I like the idea of having dedicated address spaces for
> kernel vs. user[*].
>
> Maybe we can march in that generally direction and define test's virtual address
> range to be in kernel space, i.e. the high half. I assume/hope that would play
> nice with all architectures' entry points?
yeap, it will solve the issue, virtual address range in kernel space can
be used. Also both unprivileged and privileged instruction can be
tested with ZengGuang's patch.
And is this patchset eligible to merge if common file
selftests/kvm/include/memstress.h is kept unchanged? Since it is pending
for a period of time, also LoongArch kvm selftest can pass with guest
memory size below 1.5G . We can add kernel/user mode support if
ZengGuang's patch is merged.
Regards
Bibo Mao
>
> [*] https://lore.kernel.org/all/[email protected]
>