Message-ID: <814f7ef7-48a2-a025-dcf3-5c4719cff811@quicinc.com>
Date:   Thu, 27 Jul 2023 10:28:58 -0700
From:   Elliot Berman <quic_eberman@...cinc.com>
To:     Yi-De Wu <yi-de.wu@...iatek.com>,
        Yingshiuan Pan <yingshiuan.pan@...iatek.com>,
        Ze-Yu Wang <ze-yu.wang@...iatek.com>,
        "Rob Herring" <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Jonathan Corbet <corbet@....net>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Arnd Bergmann <arnd@...db.de>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
CC:     <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-doc@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-arch@...r.kernel.org>, <linux-mediatek@...ts.infradead.org>,
        "David Bradil" <dbrazdil@...gle.com>,
        Trilok Soni <quic_tsoni@...cinc.com>,
        "Ivan Tseng" <ivan.tseng@...iatek.com>,
        Jade Shih <jades.shih@...iatek.com>,
        "My Chuang" <my.chuang@...iatek.com>,
        Shawn Hsiao <shawn.hsiao@...iatek.com>,
        PeiLun Suei <peilun.suei@...iatek.com>,
        Liju Chen <liju-clr.chen@...iatek.com>,
        Willix Yeh <chi-shen.yeh@...iatek.com>
Subject: Re: [PATCH v5 12/12] virt: geniezone: Add memory pin/unpin support

Hi Jerry,

On 7/27/2023 1:00 AM, Yi-De Wu wrote:
> From: "Jerry Wang" <ze-yu.wang@...iatek.com>
> 
> Implement memory pin/unpin.
> - use rb_tree to store pinned memory page
> - pin page when handling page fault
> - unpin page when handling relinquish or destroy
> 
> Signed-off-by: Jerry Wang <ze-yu.wang@...iatek.com>
> Signed-off-by: Liju Chen <liju-clr.chen@...iatek.com>
> Signed-off-by: Yi-De Wu <yi-de.wu@...iatek.com>
> ---
>   drivers/virt/geniezone/Makefile         |   3 +-
>   drivers/virt/geniezone/gzvm_exception.c |  32 ----
>   drivers/virt/geniezone/gzvm_hvc.c       |  34 ++++
>   drivers/virt/geniezone/gzvm_mmu.c       | 210 ++++++++++++++++++++++++
>   drivers/virt/geniezone/gzvm_vcpu.c      |   4 +-
>   drivers/virt/geniezone/gzvm_vm.c        | 113 +++----------
>   include/linux/gzvm_drv.h                |  19 ++-
>   include/uapi/linux/gzvm.h               |   5 +
>   8 files changed, 291 insertions(+), 129 deletions(-)
>   create mode 100644 drivers/virt/geniezone/gzvm_hvc.c
>   create mode 100644 drivers/virt/geniezone/gzvm_mmu.c
> 
> diff --git a/drivers/virt/geniezone/Makefile b/drivers/virt/geniezone/Makefile
> index e1299f99df76..ca4b84630573 100644
> --- a/drivers/virt/geniezone/Makefile
> +++ b/drivers/virt/geniezone/Makefile
> @@ -8,4 +8,5 @@ GZVM_DIR ?= ../../../drivers/virt/geniezone
>   
>   gzvm-y := $(GZVM_DIR)/gzvm_main.o $(GZVM_DIR)/gzvm_vm.o \
>   	  $(GZVM_DIR)/gzvm_vcpu.o $(GZVM_DIR)/gzvm_irqfd.o \
> -	  $(GZVM_DIR)/gzvm_ioeventfd.o $(GZVM_DIR)/gzvm_exception.o
> +	  $(GZVM_DIR)/gzvm_ioeventfd.o $(GZVM_DIR)/gzvm_exception.o \
> +	  $(GZVM_DIR)/gzvm_hvc.o $(GZVM_DIR)/gzvm_mmu.o
> diff --git a/drivers/virt/geniezone/gzvm_exception.c b/drivers/virt/geniezone/gzvm_exception.c
> index c2cab1472d2f..8c413815369b 100644
> --- a/drivers/virt/geniezone/gzvm_exception.c
> +++ b/drivers/virt/geniezone/gzvm_exception.c
> @@ -6,38 +6,6 @@
>   #include <linux/device.h>
>   #include <linux/gzvm_drv.h>
>   
> -/**
> - * gzvm_handle_page_fault() - Handle guest page fault, find corresponding page
> - *                            for the faulting gpa
> - * @vcpu: Pointer to struct gzvm_vcpu_run of the faulting vcpu
> - *
> - * Return:
> - * * 0			- Success to handle guest page fault
> - * * -EFAULT		- Failed to map phys addr to guest's GPA
> - */
> -static int gzvm_handle_page_fault(struct gzvm_vcpu *vcpu)
> -{
> -	struct gzvm *vm = vcpu->gzvm;
> -	int memslot_id;
> -	u64 pfn, gfn;
> -	int ret;
> -
> -	gfn = PHYS_PFN(vcpu->run->exception.fault_gpa);
> -	memslot_id = gzvm_find_memslot(vm, gfn);
> -	if (unlikely(memslot_id < 0))
> -		return -EFAULT;
> -
> -	ret = gzvm_gfn_to_pfn_memslot(&vm->memslot[memslot_id], gfn, &pfn);
> -	if (unlikely(ret))
> -		return -EFAULT;
> -
> -	ret = gzvm_arch_map_guest(vm->vm_id, memslot_id, pfn, gfn, 1);
> -	if (unlikely(ret))
> -		return -EFAULT;
> -
> -	return 0;
> -}
> -
>   /**
>    * gzvm_handle_guest_exception() - Handle guest exception
>    * @vcpu: Pointer to struct gzvm_vcpu_run in userspace
> diff --git a/drivers/virt/geniezone/gzvm_hvc.c b/drivers/virt/geniezone/gzvm_hvc.c
> new file mode 100644
> index 000000000000..d8854eeec04e
> --- /dev/null
> +++ b/drivers/virt/geniezone/gzvm_hvc.c
> @@ -0,0 +1,34 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2023 MediaTek Inc.
> + */
> +
> +#include <linux/gzvm_drv.h>
> +
> +/**
> + * gzvm_handle_guest_hvc() - Handle guest hvc
> + * @vcpu: Pointer to struct gzvm_vcpu_run in userspace
> + * Return:
> + * * true - This hvc has been processed, no need to back to VMM.
> + * * false - This hvc has not been processed, require userspace.
> + */
> +bool gzvm_handle_guest_hvc(struct gzvm_vcpu *vcpu)
> +{
> +	int ret;
> +	unsigned long ipa;
> +
> +	switch (vcpu->run->hypercall.args[0]) {
> +	case GZVM_HVC_MEM_RELINQUISH:
> +		ipa = vcpu->run->hypercall.args[1];
> +		ret = gzvm_handle_relinquish(vcpu, ipa);
> +		break;
> +	default:
> +		ret = false;
> +		break;
> +	}
> +
> +	if (!ret)
> +		return true;
> +	else
> +		return false;
> +}
> diff --git a/drivers/virt/geniezone/gzvm_mmu.c b/drivers/virt/geniezone/gzvm_mmu.c
> new file mode 100644
> index 000000000000..4c2c7da7f929
> --- /dev/null
> +++ b/drivers/virt/geniezone/gzvm_mmu.c
> @@ -0,0 +1,210 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (c) 2023 MediaTek Inc.
> + */
> +
> +#include <linux/gzvm_drv.h>
> +
> +/**
> + * hva_to_pa_fast() - converts hva to pa in generic fast way
> + * @hva: Host virtual address.
> + *
> + * Return: 0 if translation error
> + */
> +u64 hva_to_pa_fast(u64 hva)
> +{
> +	struct page *page[1];
> +
> +	u64 pfn;
> +
> +	if (get_user_page_fast_only(hva, 0, page)) {
> +		pfn = page_to_phys(page[0]);
> +		put_page((struct page *)page);
> +		return pfn;
> +	} else {
> +		return 0;
> +	}
> +}
> +
> +/**
> + * hva_to_pa_slow() - note that this function may sleep
> + * @hva: Host virtual address.
> + *
> + * Return: 0 if translation error
> + */
> +u64 hva_to_pa_slow(u64 hva)
> +{
> +	struct page *page = NULL;
> +	u64 pfn = 0;
> +	int npages;
> +
> +	npages = get_user_pages_unlocked(hva, 1, &page, 0);
> +	if (npages != 1)
> +		return 0;
> +
> +	if (page) {
> +		pfn = page_to_phys(page);
> +		put_page(page);
> +	}
> +
> +	return pfn;
> +}
> +
> +static u64 __gzvm_gfn_to_pfn_memslot(struct gzvm_memslot *memslot, u64 gfn)
> +{
> +	u64 hva, pa;
> +
> +	hva = gzvm_gfn_to_hva_memslot(memslot, gfn);
> +
> +	pa = gzvm_hva_to_pa_arch(hva);
> +	if (pa != 0)
> +		return PHYS_PFN(pa);
> +
> +	pa = hva_to_pa_fast(hva);
> +	if (pa)
> +		return PHYS_PFN(pa);
> +
> +	pa = hva_to_pa_slow(hva);
> +	if (pa)
> +		return PHYS_PFN(pa);
> +
> +	return 0;
> +}
> +
> +/**
> + * gzvm_gfn_to_pfn_memslot() - Translate gfn (guest ipa) to pfn (host pa),
> + *			       result is in @pfn
> + * @memslot: Pointer to struct gzvm_memslot.
> + * @gfn: Guest frame number.
> + * @pfn: Host page frame number.
> + *
> + * Return:
> + * * 0			- Succeed
> + * * -EFAULT		- Failed to convert
> + */
> +int gzvm_gfn_to_pfn_memslot(struct gzvm_memslot *memslot, u64 gfn, u64 *pfn)
> +{
> +	u64 __pfn;
> +
> +	if (!memslot)
> +		return -EFAULT;
> +
> +	__pfn = __gzvm_gfn_to_pfn_memslot(memslot, gfn);
> +	if (__pfn == 0) {
> +		*pfn = 0;
> +		return -EFAULT;
> +	}
> +
> +	*pfn = __pfn;
> +
> +	return 0;
> +}
> +
> +static int cmp_ppages(struct rb_node *node, const struct rb_node *parent)
> +{
> +	struct gzvm_pinned_page *a = container_of(node, struct gzvm_pinned_page, node);
> +	struct gzvm_pinned_page *b = container_of(parent, struct gzvm_pinned_page, node);
> +
> +	if (a->ipa < b->ipa)
> +		return -1;
> +	if (a->ipa > b->ipa)
> +		return 1;
> +	return 0;
> +}
> +
> +static int rb_ppage_cmp(const void *key, const struct rb_node *node)
> +{
> +	struct gzvm_pinned_page *p = container_of(node, struct gzvm_pinned_page, node);
> +	phys_addr_t ipa = (phys_addr_t)key;
> +
> +	return (ipa < p->ipa) ? -1 : (ipa > p->ipa);
> +}
> +
> +static int gzvm_insert_ppage(struct gzvm *vm, struct gzvm_pinned_page *ppage)
> +{
> +	if (rb_find_add(&ppage->node, &vm->pinned_pages, cmp_ppages))
> +		return -EEXIST;
> +	return 0;
> +}
> +
> +static int pin_one_page(unsigned long hva, struct page **page)
> +{
> +	struct mm_struct *mm = current->mm;
> +	unsigned int flags = FOLL_HWPOISON | FOLL_LONGTERM | FOLL_WRITE;

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> +
> +	mmap_read_lock(mm);
> +	pin_user_pages(hva, 1, flags, page);
> +	mmap_read_unlock(mm);
> +
> +	return 0;
> +}
> +
> +/**
> + * gzvm_handle_relinquish() - Handle memory relinquish request from hypervisor
> + *
> + * @vcpu: Pointer to struct gzvm_vcpu_run in userspace
> + * @ipa: Start address(gpa) of a reclaimed page
> + */
> +int gzvm_handle_relinquish(struct gzvm_vcpu *vcpu, phys_addr_t ipa)
> +{
> +	struct gzvm_pinned_page *ppage;
> +	struct rb_node *node;
> +	struct gzvm *vm = vcpu->gzvm;
> +
> +	node = rb_find((void *)ipa, &vm->pinned_pages, rb_ppage_cmp);
> +
> +	if (node)
> +		rb_erase(node, &vm->pinned_pages);
> +	else
> +		return 0;
> +
> +	ppage = container_of(node, struct gzvm_pinned_page, node);
> +	unpin_user_pages_dirty_lock(&ppage->page, 1, true);
> +	kfree(ppage);
> +	return 0;
> +}
> +
> +/**
> + * gzvm_handle_page_fault() - Handle guest page fault, find corresponding page
> + * for the faulting gpa
> + * @vcpu: Pointer to struct gzvm_vcpu_run in userspace
> + */
> +int gzvm_handle_page_fault(struct gzvm_vcpu *vcpu)
> +{
> +	struct gzvm *vm = vcpu->gzvm;
> +	int memslot_id;
> +	u64 pfn, gfn;
> +	unsigned long hva;
> +	struct gzvm_pinned_page *ppage = NULL;
> +	struct page *page = NULL;
> +	int ret;
> +
> +	gfn = PHYS_PFN(vcpu->run->exception.fault_gpa);
> +	memslot_id = gzvm_find_memslot(vm, gfn);
> +	if (unlikely(memslot_id < 0))
> +		return -EFAULT;
> +
> +	ret = gzvm_gfn_to_pfn_memslot(&vm->memslot[memslot_id], gfn, &pfn);
> +	if (unlikely(ret))
> +		return -EFAULT;
> +
> +	ret = gzvm_arch_map_guest(vm->vm_id, memslot_id, pfn, gfn, 1);
> +	if (unlikely(ret))
> +		return -EFAULT;
> +
> +	hva = gzvm_gfn_to_hva_memslot(&vm->memslot[memslot_id], gfn);
> +	pin_one_page(hva, &page);
> +
> +	if (!page)
> +		return -EFAULT;
> +
> +	ppage = kmalloc(sizeof(*ppage), GFP_KERNEL_ACCOUNT);
> +	if (!ppage)
> +		return -ENOMEM;
> +
> +	ppage->page = page;
> +	ppage->ipa = vcpu->run->exception.fault_gpa;
> +	gzvm_insert_ppage(vm, ppage);
> +
> +	return 0;
> +}
> diff --git a/drivers/virt/geniezone/gzvm_vcpu.c b/drivers/virt/geniezone/gzvm_vcpu.c
> index 794b24da40e2..964e18ff0d2a 100644
> --- a/drivers/virt/geniezone/gzvm_vcpu.c
> +++ b/drivers/virt/geniezone/gzvm_vcpu.c
> @@ -117,7 +117,9 @@ static long gzvm_vcpu_run(struct gzvm_vcpu *vcpu, void * __user argp)
>   				need_userspace = true;
>   			break;
>   		case GZVM_EXIT_HYPERCALL:
> -			fallthrough;
> +			if (!gzvm_handle_guest_hvc(vcpu))
> +				need_userspace = true;
> +			break;
>   		case GZVM_EXIT_DEBUG:
>   			fallthrough;
>   		case GZVM_EXIT_FAIL_ENTRY:
> diff --git a/drivers/virt/geniezone/gzvm_vm.c b/drivers/virt/geniezone/gzvm_vm.c
> index 3da5fdc141b6..6fae6bf976c8 100644
> --- a/drivers/virt/geniezone/gzvm_vm.c
> +++ b/drivers/virt/geniezone/gzvm_vm.c
> @@ -16,106 +16,13 @@
>   static DEFINE_MUTEX(gzvm_list_lock);
>   static LIST_HEAD(gzvm_list);
>   
> -/**
> - * hva_to_pa_fast() - converts hva to pa in generic fast way
> - * @hva: Host virtual address.
> - *
> - * Return: 0 if translation error
> - */
> -static u64 hva_to_pa_fast(u64 hva)
> -{
> -	struct page *page[1];
> -
> -	u64 pfn;
> -
> -	if (get_user_page_fast_only(hva, 0, page)) {
> -		pfn = page_to_phys(page[0]);
> -		put_page((struct page *)page);
> -		return pfn;
> -	} else {
> -		return 0;
> -	}
> -}
> -
> -/**
> - * hva_to_pa_slow() - note that this function may sleep
> - * @hva: Host virtual address.
> - *
> - * Return: 0 if translation error
> - */
> -static u64 hva_to_pa_slow(u64 hva)
> -{
> -	struct page *page;
> -	int npages;
> -	u64 pfn;
> -
> -	npages = get_user_pages_unlocked(hva, 1, &page, 0);
> -	if (npages != 1)
> -		return 0;
> -
> -	pfn = page_to_phys(page);
> -	put_page(page);
> -
> -	return pfn;
> -}
> -
> -static u64 gzvm_gfn_to_hva_memslot(struct gzvm_memslot *memslot, u64 gfn)
> +u64 gzvm_gfn_to_hva_memslot(struct gzvm_memslot *memslot, u64 gfn)
>   {
>   	u64 offset = gfn - memslot->base_gfn;
>   
>   	return memslot->userspace_addr + offset * PAGE_SIZE;
>   }
>   
> -static u64 __gzvm_gfn_to_pfn_memslot(struct gzvm_memslot *memslot, u64 gfn)
> -{
> -	u64 hva, pa;
> -
> -	hva = gzvm_gfn_to_hva_memslot(memslot, gfn);
> -
> -	pa = gzvm_hva_to_pa_arch(hva);
> -	if (pa != 0)
> -		return PHYS_PFN(pa);
> -
> -	pa = hva_to_pa_fast(hva);
> -	if (pa)
> -		return PHYS_PFN(pa);
> -
> -	pa = hva_to_pa_slow(hva);
> -	if (pa)
> -		return PHYS_PFN(pa);
> -
> -	return 0;
> -}
> -
> -/**
> - * gzvm_gfn_to_pfn_memslot() - Translate gfn (guest ipa) to pfn (host pa),
> - *			       result is in @pfn
> - * @memslot: Pointer to struct gzvm_memslot.
> - * @gfn: Guest frame number.
> - * @pfn: Host page frame number.
> - *
> - * Return:
> - * * 0			- Succeed
> - * * -EFAULT		- Failed to convert
> - */
> -int gzvm_gfn_to_pfn_memslot(struct gzvm_memslot *memslot, u64 gfn, u64 *pfn)
> -{
> -	u64 __pfn;
> -
> -	if (!memslot)
> -		return -EFAULT;
> -
> -	__pfn = __gzvm_gfn_to_pfn_memslot(memslot, gfn);
> -	if (__pfn == 0) {
> -		*pfn = 0;
> -		return -EFAULT;
> -	}
> -
> -	*pfn = __pfn;
> -
> -	return 0;
> -}
> -
>   /**
>    * gzvm_find_memslot() - Find memslot containing this @gpa
>    * @vm: Pointer to struct gzvm
> @@ -454,6 +361,21 @@ static long gzvm_vm_ioctl(struct file *filp, unsigned int ioctl,
>   	return ret;
>   }
>   
> +static void gzvm_destroy_ppage(struct gzvm *gzvm)
> +{
> +	struct gzvm_pinned_page *ppage;
> +	struct rb_node *node;
> +
> +	node = rb_first(&gzvm->pinned_pages);
> +	while (node) {
> +		ppage = rb_entry(node, struct gzvm_pinned_page, node);
> +		unpin_user_pages_dirty_lock(&ppage->page, 1, true);
> +		node = rb_next(node);
> +		rb_erase(&ppage->node, &gzvm->pinned_pages);
> +		kfree(ppage);
> +	}
> +}
> +
>   static void gzvm_destroy_vm(struct gzvm *gzvm)
>   {
>   	pr_debug("VM-%u is going to be destroyed\n", gzvm->vm_id);
> @@ -470,6 +392,8 @@ static void gzvm_destroy_vm(struct gzvm *gzvm)
>   
>   	mutex_unlock(&gzvm->lock);
>   
> +	gzvm_destroy_ppage(gzvm);
> +
>   	kfree(gzvm);
>   }
>   
> @@ -505,6 +429,7 @@ static struct gzvm *gzvm_create_vm(unsigned long vm_type)
>   	gzvm->vm_id = ret;
>   	gzvm->mm = current->mm;
>   	mutex_init(&gzvm->lock);
> +	gzvm->pinned_pages = RB_ROOT;
>   
>   	ret = gzvm_vm_irqfd_init(gzvm);
>   	if (ret) {
> diff --git a/include/linux/gzvm_drv.h b/include/linux/gzvm_drv.h
> index d7838679c700..a0bc3b4244cc 100644
> --- a/include/linux/gzvm_drv.h
> +++ b/include/linux/gzvm_drv.h
> @@ -12,6 +12,8 @@
>   #include <linux/mutex.h>
>   #include <linux/gzvm.h>
>   #include <linux/srcu.h>
> +#include <linux/rbtree.h>
> +#include <linux/mm.h>
>   
>   #define GZVM_VCPU_MMAP_SIZE  PAGE_SIZE
>   #define INVALID_VM_ID   0xffff
> @@ -76,6 +78,12 @@ struct gzvm_vcpu {
>   	struct hrtimer gzvm_mtimer;
>   };
>   
> +struct gzvm_pinned_page {
> +	struct rb_node node;
> +	struct page *page;
> +	u64 ipa;
> +};
> +
>   struct gzvm {
>   	struct gzvm_vcpu *vcpus[GZVM_MAX_VCPUS];
>   	/* userspace tied to this vm */
> @@ -102,6 +110,9 @@ struct gzvm {
>   	struct srcu_struct irq_srcu;
>   	/* lock for irq injection */
>   	struct mutex irq_lock;
> +
> +	/* Use rb-tree to record pin/unpin page */
> +	struct rb_root pinned_pages;
>   };
>   
>   long gzvm_dev_ioctl_check_extension(struct gzvm *gzvm, unsigned long args);
> @@ -137,9 +148,15 @@ int gzvm_arch_inform_exit(u16 vm_id);
>   int gzvm_arch_drv_init(void);
>   void gzvm_arch_drv_exit(void);
>   
> -int gzvm_gfn_to_pfn_memslot(struct gzvm_memslot *memslot, u64 gfn, u64 *pfn);
>   int gzvm_find_memslot(struct gzvm *vm, u64 gpa);
> +int gzvm_gfn_to_pfn_memslot(struct gzvm_memslot *memslot, u64 gfn, u64 *pfn);
> +u64 gzvm_gfn_to_hva_memslot(struct gzvm_memslot *memslot, u64 gfn);
> +u64 hva_to_pa_fast(u64 hva);
> +u64 hva_to_pa_slow(u64 hva);
> +int gzvm_handle_page_fault(struct gzvm_vcpu *vcpu);
> +int gzvm_handle_relinquish(struct gzvm_vcpu *vcpu, phys_addr_t ipa);
>   bool gzvm_handle_guest_exception(struct gzvm_vcpu *vcpu);
> +bool gzvm_handle_guest_hvc(struct gzvm_vcpu *vcpu);
>   
>   int gzvm_arch_create_device(u16 vm_id, struct gzvm_create_device *gzvm_dev);
>   int gzvm_arch_inject_irq(struct gzvm *gzvm, unsigned int vcpu_idx,
> diff --git a/include/uapi/linux/gzvm.h b/include/uapi/linux/gzvm.h
> index a3329b713089..74b959994c4a 100644
> --- a/include/uapi/linux/gzvm.h
> +++ b/include/uapi/linux/gzvm.h
> @@ -156,6 +156,11 @@ enum {
>   	GZVM_EXCEPTION_PAGE_FAULT = 0x1,
>   };
>   
> +/* hypercall definitions of GZVM_EXIT_HYPERCALL */
> +enum {
> +	GZVM_HVC_MEM_RELINQUISH = 0xc6000009,
> +};
> +
>   /**
>    * struct gzvm_vcpu_run: Same purpose as kvm_run, this struct is
>    *			shared between userspace, kernel and

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