RE: [PATCH v5 06/16] x86/hyperv: allocate output arg pages if required
From: Wei Liu Sent: Wednesday, January 20, 2021 4:01 AM
>
> When Linux runs as the root partition, it will need to make hypercalls
> which return data from the hypervisor.
>
> Allocate pages for storing results when Linux runs as the root
> partition.
>
> Signed-off-by: Lillian Grassin-Drake
> Co-Developed-by: Lillian Grassin-Drake
> Signed-off-by: Wei Liu
> ---
> v3: Fix hv_cpu_die to use free_pages.
> v2: Address Vitaly's comments
> ---
> arch/x86/hyperv/hv_init.c | 35 -
> arch/x86/include/asm/mshyperv.h | 1 +
> 2 files changed, 31 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index e04d90af4c27..6f4cb40e53fe 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -41,6 +41,9 @@ EXPORT_SYMBOL_GPL(hv_vp_assist_page);
> void __percpu **hyperv_pcpu_input_arg;
> EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
>
> +void __percpu **hyperv_pcpu_output_arg;
> +EXPORT_SYMBOL_GPL(hyperv_pcpu_output_arg);
> +
> u32 hv_max_vp_index;
> EXPORT_SYMBOL_GPL(hv_max_vp_index);
>
> @@ -73,12 +76,19 @@ static int hv_cpu_init(unsigned int cpu)
> void **input_arg;
> struct page *pg;
>
> - input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
> /* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
> - pg = alloc_page(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL);
> + pg = alloc_pages(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL,
> hv_root_partition ?
> 1 : 0);
> if (unlikely(!pg))
> return -ENOMEM;
> +
> + input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
> *input_arg = page_address(pg);
> + if (hv_root_partition) {
> + void **output_arg;
> +
> + output_arg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
> + *output_arg = page_address(pg + 1);
> + }
>
> hv_get_vp_index(msr_vp_index);
>
> @@ -205,14 +215,23 @@ static int hv_cpu_die(unsigned int cpu)
> unsigned int new_cpu;
> unsigned long flags;
> void **input_arg;
> - void *input_pg = NULL;
> + void *pg;
>
> local_irq_save(flags);
> input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
> - input_pg = *input_arg;
> + pg = *input_arg;
> *input_arg = NULL;
> +
> + if (hv_root_partition) {
> + void **output_arg;
> +
> + output_arg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
> + *output_arg = NULL;
> + }
> +
> local_irq_restore(flags);
> - free_page((unsigned long)input_pg);
> +
> + free_pages((unsigned long)pg, hv_root_partition ? 1 : 0);
>
> if (hv_vp_assist_page && hv_vp_assist_page[cpu])
> wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
> @@ -346,6 +365,12 @@ void __init hyperv_init(void)
>
> BUG_ON(hyperv_pcpu_input_arg == NULL);
>
> + /* Allocate the per-CPU state for output arg for root */
> + if (hv_root_partition) {
> + hyperv_pcpu_output_arg = alloc_percpu(void *);
> + BUG_ON(hyperv_pcpu_output_arg == NULL);
> + }
> +
> /* Allocate percpu VP index */
> hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
> GFP_KERNEL);
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index ac2b0d110f03..62d9390f1ddf 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -76,6 +76,7 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
> #if IS_ENABLED(CONFIG_HYPERV)
> extern void *hv_hypercall_pg;
> extern void __percpu **hyperv_pcpu_input_arg;
> +extern void __percpu **hyperv_pcpu_output_arg;
>
> static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
> {
> --
> 2.20.1
I think this all works OK. But a meta question: Do we need a separate
per-cpu output argument page? From the Hyper-V hypercall standpoint, I
don't think input and output args need to be in separate pages. They both
just need to not cross a page boundary. As long as we don't have a hypercall
where the sum of the sizes of the input and output args exceeds a page,
we could just have a single page, and split it up in any manner that works
for the particular hypercall.
Thoughts?
Michael
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Re: [PATCH v5 06/16] x86/hyperv: allocate output arg pages if required
On Wed, Jan 20, 2021 at 7:01 AM Wei Liu wrote:
>
> When Linux runs as the root partition, it will need to make hypercalls
> which return data from the hypervisor.
>
> Allocate pages for storing results when Linux runs as the root
> partition.
>
> Signed-off-by: Lillian Grassin-Drake
> Co-Developed-by: Lillian Grassin-Drake
> Signed-off-by: Wei Liu
Reviewed-by: Pavel Tatashin
The new warnings reported by the robot are the same as for the input argument.
Pasha
> ---
> v3: Fix hv_cpu_die to use free_pages.
> v2: Address Vitaly's comments
> ---
> arch/x86/hyperv/hv_init.c | 35 -
> arch/x86/include/asm/mshyperv.h | 1 +
> 2 files changed, 31 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
> index e04d90af4c27..6f4cb40e53fe 100644
> --- a/arch/x86/hyperv/hv_init.c
> +++ b/arch/x86/hyperv/hv_init.c
> @@ -41,6 +41,9 @@ EXPORT_SYMBOL_GPL(hv_vp_assist_page);
> void __percpu **hyperv_pcpu_input_arg;
> EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
>
> +void __percpu **hyperv_pcpu_output_arg;
> +EXPORT_SYMBOL_GPL(hyperv_pcpu_output_arg);
> +
> u32 hv_max_vp_index;
> EXPORT_SYMBOL_GPL(hv_max_vp_index);
>
> @@ -73,12 +76,19 @@ static int hv_cpu_init(unsigned int cpu)
> void **input_arg;
> struct page *pg;
>
> - input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
> /* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
> - pg = alloc_page(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL);
> + pg = alloc_pages(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL,
> hv_root_partition ? 1 : 0);
> if (unlikely(!pg))
> return -ENOMEM;
> +
> + input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
> *input_arg = page_address(pg);
> + if (hv_root_partition) {
> + void **output_arg;
> +
> + output_arg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
> + *output_arg = page_address(pg + 1);
> + }
>
> hv_get_vp_index(msr_vp_index);
>
> @@ -205,14 +215,23 @@ static int hv_cpu_die(unsigned int cpu)
> unsigned int new_cpu;
> unsigned long flags;
> void **input_arg;
> - void *input_pg = NULL;
> + void *pg;
>
> local_irq_save(flags);
> input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
> - input_pg = *input_arg;
> + pg = *input_arg;
> *input_arg = NULL;
> +
> + if (hv_root_partition) {
> + void **output_arg;
> +
> + output_arg = (void **)this_cpu_ptr(hyperv_pcpu_output_arg);
> + *output_arg = NULL;
> + }
> +
> local_irq_restore(flags);
> - free_page((unsigned long)input_pg);
> +
> + free_pages((unsigned long)pg, hv_root_partition ? 1 : 0);
>
> if (hv_vp_assist_page && hv_vp_assist_page[cpu])
> wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
> @@ -346,6 +365,12 @@ void __init hyperv_init(void)
>
> BUG_ON(hyperv_pcpu_input_arg == NULL);
>
> + /* Allocate the per-CPU state for output arg for root */
> + if (hv_root_partition) {
> + hyperv_pcpu_output_arg = alloc_percpu(void *);
> + BUG_ON(hyperv_pcpu_output_arg == NULL);
> + }
> +
> /* Allocate percpu VP index */
> hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
> GFP_KERNEL);
> diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
> index ac2b0d110f03..62d9390f1ddf 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -76,6 +76,7 @@ static inline void hv_disable_stimer0_percpu_irq(int irq) {}
> #if IS_ENABLED(CONFIG_HYPERV)
> extern void *hv_hypercall_pg;
> extern void __percpu **hyperv_pcpu_input_arg;
> +extern void __percpu **hyperv_pcpu_output_arg;
>
> static inline u64 hv_do_hypercall(u64 control, void *input, void *output)
> {
> --
> 2.20.1
>
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Re: [PATCH v5 06/16] x86/hyperv: allocate output arg pages if required
Hi Wei,
I love your patch! Perhaps something to improve:
[auto build test WARNING on e71ba9452f0b5b2e8dc8aa5445198cd9214a6a62]
url:
https://github.com/0day-ci/linux/commits/Wei-Liu/Introducing-Linux-root-partition-support-for-Microsoft-Hypervisor/20210120-215640
base:e71ba9452f0b5b2e8dc8aa5445198cd9214a6a62
config: x86_64-randconfig-s021-20210120 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
# apt-get install sparse
# sparse version: v0.6.3-208-g46a52ca4-dirty
#
https://github.com/0day-ci/linux/commit/f93337fc44e13a1506633f5d308bf74a8311dada
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review
Wei-Liu/Introducing-Linux-root-partition-support-for-Microsoft-Hypervisor/20210120-215640
git checkout f93337fc44e13a1506633f5d308bf74a8311dada
# save the attached .config to linux build tree
make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=x86_64
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot
"sparse warnings: (new ones prefixed by >>)"
arch/x86/hyperv/hv_init.c:84:30: sparse: sparse: incorrect type in
initializer (different address spaces) @@ expected void const [noderef]
__percpu *__vpp_verify @@ got void [noderef] __percpu ** @@
arch/x86/hyperv/hv_init.c:84:30: sparse: expected void const [noderef]
__percpu *__vpp_verify
arch/x86/hyperv/hv_init.c:84:30: sparse: got void [noderef] __percpu **
arch/x86/hyperv/hv_init.c:89:39: sparse: sparse: incorrect type in
initializer (different address spaces) @@ expected void const [noderef]
__percpu *__vpp_verify @@ got void [noderef] __percpu ** @@
arch/x86/hyperv/hv_init.c:89:39: sparse: expected void const [noderef]
__percpu *__vpp_verify
arch/x86/hyperv/hv_init.c:89:39: sparse: got void [noderef] __percpu **
arch/x86/hyperv/hv_init.c:221:30: sparse: sparse: incorrect type in
initializer (different address spaces) @@ expected void const [noderef]
__percpu *__vpp_verify @@ got void [noderef] __percpu ** @@
arch/x86/hyperv/hv_init.c:221:30: sparse: expected void const [noderef]
__percpu *__vpp_verify
arch/x86/hyperv/hv_init.c:221:30: sparse: got void [noderef] __percpu **
arch/x86/hyperv/hv_init.c:228:39: sparse: sparse: incorrect type in
initializer (different address spaces) @@ expected void const [noderef]
__percpu *__vpp_verify @@ got void [noderef] __percpu ** @@
arch/x86/hyperv/hv_init.c:228:39: sparse: expected void const [noderef]
__percpu *__vpp_verify
arch/x86/hyperv/hv_init.c:228:39: sparse: got void [noderef] __percpu **
arch/x86/hyperv/hv_init.c:364:31: sparse: sparse: incorrect type in
assignment (different address spaces) @@ expected void [noderef] __percpu
**extern [addressable] [toplevel] hyperv_pcpu_input_arg @@ got void
*[noderef] __percpu * @@
arch/x86/hyperv/hv_init.c:364:31: sparse: expected void [noderef]
__percpu **extern [addressable] [toplevel] hyperv_pcpu_input_arg
arch/x86/hyperv/hv_init.c:364:31: sparse: got void *[noderef] __percpu *
>> arch/x86/hyperv/hv_init.c:370:40: sparse: sparse: incorrect type in
>> assignment (different address spaces) @@ expected void [noderef]
>> __percpu **extern [addressable] [toplevel] hyperv_pcpu_output_arg @@ got
>> void *[noderef] __percpu * @@
arch/x86/hyperv/hv_init.c:370:40: sparse: expected void [noderef]
__percpu **extern [addressable] [toplevel] hyperv_pcpu_output_arg
arch/x86/hyperv/hv_init.c:370:40: sparse: got void *[noderef] __percpu *
vim +370 arch/x86/hyperv/hv_init.c
211
212 static int hv_cpu_die(unsigned int cpu)
213 {
214 struct hv_reenlightenment_control re_ctrl;
215 unsigned int new_cpu;
216 unsigned long flags;
217 void **input_arg;
218 void *pg;
219
220 local_irq_save(flags);
> 221 input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
222 pg = *input_arg;
223 *input_arg = NULL;
224
225 if (hv_root_partition) {
226 void **output_arg;
227
228 output_arg = (void
**)this_cpu_ptr(hyperv_pcpu_output_arg);
229 *output_arg = NULL;
230 }
231
232 local_irq_restore(flags);
233
234 free_pages((unsigned long)pg, hv_root_partition ? 1 : 0);
235
236 if (hv_vp_assist_page && hv_vp_assist_page[cpu])
237 wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
238
239 if (hv_reenlightenment_cb == NULL)
240 return 0;
241
242 rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)_ctrl));
243 if (re_ctrl.target_vp == hv_vp_index[cpu]) {
244 /*
245 * Reassign
