linux-kernel - Re: [RFC v1 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page with the hypervisor.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <af0a236f-37b2-ee16-0ebd-576b4e12d8cd@ozlabs.ru>
Date:   Wed, 6 Nov 2019 12:58:50 +1100
From:   Alexey Kardashevskiy <aik@...abs.ru>
To:     Ram Pai <linuxram@...ibm.com>, linuxppc-dev@...ts.ozlabs.org
Cc:     benh@...nel.crashing.org, david@...son.dropbear.id.au,
        mpe@...erman.id.au, paulus@...abs.org, mdroth@...ux.vnet.ibm.com,
        hch@....de, andmike@...ibm.com, sukadev@...ux.vnet.ibm.com,
        mst@...hat.com, ram.n.pai@...il.com, cai@....pw,
        tglx@...utronix.de, bauerman@...ux.ibm.com,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC v1 1/2] powerpc/pseries/iommu: Share the per-cpu TCE page
 with the hypervisor.



On 05/11/2019 08:28, Ram Pai wrote:
> The hypervisor needs to access the contents of the page holding the TCE
> entries while setting up the TCE entries in the IOMMU's TCE table. For
> SecureVMs, since this page is encrypted, the hypervisor cannot access
> valid entries. Share the page with the hypervisor. This ensures that the
> hypervisor sees the valid entries.
> 
> Signed-off-by: Ram Pai <linuxram@...ibm.com>
> ---
>  arch/powerpc/platforms/pseries/iommu.c | 20 +++++++++++++++++---
>  1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 8d9c2b1..07f0847 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -37,6 +37,7 @@
>  #include <asm/mmzone.h>
>  #include <asm/plpar_wrappers.h>
>  #include <asm/svm.h>
> +#include <asm/ultravisor.h>
>  
>  #include "pseries.h"
>  
> @@ -179,6 +180,19 @@ static int tce_build_pSeriesLP(struct iommu_table *tbl, long tcenum,
>  
>  static DEFINE_PER_CPU(__be64 *, tce_page);
>  
> +/*
> + * Allocate a tce page.  If secure VM, share the page with the hypervisor.
> + */
> +static __be64 *alloc_tce_page(void)
> +{
> +	__be64 *tcep = (__be64 *)__get_free_page(GFP_ATOMIC);
> +
> +	if (tcep && is_secure_guest())
> +		uv_share_page(PHYS_PFN(__pa(tcep)), 1);


There is no matching unshare in this patch.


> +
> +	return tcep;
> +}
> +
>  static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
>  				     long npages, unsigned long uaddr,
>  				     enum dma_data_direction direction,
> @@ -206,8 +220,7 @@ static int tce_buildmulti_pSeriesLP(struct iommu_table *tbl, long tcenum,
>  	 * from iommu_alloc{,_sg}()
>  	 */
>  	if (!tcep) {
> -		tcep = (__be64 *)__get_free_page(GFP_ATOMIC);
> -		/* If allocation fails, fall back to the loop implementation */
> +		tcep = alloc_tce_page();
>  		if (!tcep) {
>  			local_irq_restore(flags);
>  			return tce_build_pSeriesLP(tbl, tcenum, npages, uaddr,
> @@ -391,6 +404,7 @@ static int tce_clearrange_multi_pSeriesLP(unsigned long start_pfn,
>  	return rc;
>  }
>  
> +

Unrelated.


>  static int tce_setrange_multi_pSeriesLP(unsigned long start_pfn,
>  					unsigned long num_pfn, const void *arg)
>  {
> @@ -405,7 +419,7 @@ static int tce_setrange_multi_pSeriesLP(unsigned long start_pfn,
>  	tcep = __this_cpu_read(tce_page);
>  
>  	if (!tcep) {
> -		tcep = (__be64 *)__get_free_page(GFP_ATOMIC);
> +		tcep = alloc_tce_page();
>  		if (!tcep) {
>  			local_irq_enable();
>  			return -ENOMEM;
> 

-- 
Alexey