#include <bits/stdc++.h>
using namespace std;
//#define OPENIOBUF

namespace FastIO
{

class FastIOBase
{
 protected:
#ifdef OPENIOBUF
	static const int BUFSIZE=1<<22;
	char buf[BUFSIZE+1];
	int buf_p=0;
#endif
	FILE *target;
 public:
#ifdef OPENIOBUF
	virtual void flush()=0;
#endif
	FastIOBase(FILE *f): target(f){}
	~FastIOBase()=default;
};

class FastOutput: public FastIOBase
{
#ifdef OPENIOBUF
 public:
	inline void flush()
		{ fwrite(buf,1,buf_p,target),buf_p=0; }
#endif
 protected:
	inline void __putc(char x)
	{
#ifdef OPENIOBUF
		if(buf[buf_p++]=x,buf_p==BUFSIZE)flush();
#else
		putc(x,target);
#endif
	}
	template<typename T>
	inline void __write(T x)
	{
		static char stk[64],*top;top=stk;
		if(x<0) return __putc('-'),__write(-x);
		do *(top++)=x%10,x/=10; while(x);
		for(;top!=stk;__putc(*(--top)+'0'));
	}
 public:
	FastOutput(FILE *f=stdout): FastIOBase(f){}
#ifdef OPENIOBUF
	inline void setTarget(FILE *f) { this->flush(),target=f; }
	~FastOutput(){ flush(); }
#else
	inline void setTarget(FILE *f) { target=f; }
#endif
	template<typename ...T>
	inline void writesp(const T &...x)
		{ initializer_list<int>{(this->operator<<(x),__putc(' '),0)...}; }
	template<typename ...T>
	inline void writeln(const T &...x)
		{ initializer_list<int>{(this->operator<<(x),__putc('\n'),0)...}; }
	inline FastOutput &operator <<(char x)
		{ return __putc(x),*this; }
	inline FastOutput &operator <<(const char *s)
		{ for(;*s;__putc(*(s++)));return *this; }
	inline FastOutput &operator <<(const string &s)
		{ return (*this)<<s.c_str(); }
	template<typename T,typename=typename enable_if<is_integral<T>::value>::type>
	inline FastOutput &operator <<(const T &x)
		{ return __write(x),*this; }
}qout;

class FastInput: public FastIOBase
{
#ifdef OPENIOBUF
 public:
	inline void flush()
		{ buf[fread(buf,1,BUFSIZE,target)]='\0',buf_p=0; }
#endif
 protected:
	inline char __getc()
	{
#ifdef OPENIOBUF
		if(buf_p==BUFSIZE) flush();
		return buf[buf_p++];
#else
		return getc(target);
#endif
	}
 public:
#ifdef OPENIOBUF
	FastInput(FILE *f=stdin): FastIOBase(f){ buf_p=BUFSIZE; }
	inline void setTarget(FILE *f) { this->flush(),target=f; }
#else
	FastInput(FILE *f=stdin): FastIOBase(f){}
	inline void setTarget(FILE *f) { target=f; }
#endif
	inline char getchar() { return __getc(); }
	template<typename ...T>
	inline void read(T &...x)
		{ initializer_list<int>{(this->operator>>(x),0)...}; }
	inline FastInput &operator >>(char &x)
		{ while(isspace(x=__getc()));return *this; }
	template<typename T,typename=typename enable_if<is_integral<T>::value>::type>
	inline FastInput &operator >>(T &x)
	{
		static char ch,sym;x=sym=0;
		while(isspace(ch=__getc()));
		if(ch=='-') sym=1,ch=__getc();
		for(;isdigit(ch);x=(x<<1)+(x<<3)+(ch^48),ch=__getc());
		return sym?x=-x:x,*this;
	}
	inline FastInput &operator >>(char *s)
	{
		while(isspace(*s=__getc()));
		for(;!isspace(*s) && *s && ~*s;*(++s)=__getc());
		return *s='\0',*this;
	}
	inline FastInput &operator >>(string &s)
	{
		char str_buf[(1<<8)+1],*p=str_buf;
		char *const buf_end=str_buf+(1<<8);
		while(isspace(*p=__getc()));
		for(s.clear(),p++;;p=str_buf)
		{
			for(;p!=buf_end && !isspace(*p=__getc()) && *p && ~*p;p++);
			*p='\0',s.append(str_buf);
			if(p!=buf_end) break;
		}
		return *this;
	}
}qin;

} // namespace FastIO
using namespace FastIO;

using LL=long long;
using LD=long double;
using UI=unsigned int;
using ULL=unsigned long long;
constexpr int INF=1e9;

#ifndef DADALZY
#define FILEIO(file) freopen(file".in","r",stdin),freopen(file".out","w",stdout)
#else
#define FILEIO(file)
#endif

int T,n,m;
vector<string> a;
vector<int> manacher(const string &str)
{
	static char s[2000005];
	static int p[2000005];
	int len=0;
	for(auto &c: str) s[++len]='#',s[++len]=c;
	s[++len]='#',s[0]='$',s[len+1]='\0';
	int pos=0,mx=0;
	for(int i=1;i<=len;i++)
	{
		if(i<=mx) p[i]=min(mx-i+1,p[pos*2-i]);
		while(s[i-p[i]]==s[i+p[i]]) p[i]++;
		if(i+p[i]>mx) mx=i+p[i]-1,pos=i;
	}
	vector<int> res(len-2);
	for(int i=2;i<len;i++) res[i-2]=(p[i]>>1);
	return res;
}
vector<vector<int>> Rr,Cr;
void getR()
{
	Rr=Cr=vector(n,vector(m,0));
	for(int i=0;i<n;i++)
	{
		string tmp(a[i]);
		auto res=manacher(tmp);
		for(int j=0;j+1<m;j++) Rr[i][j]=res[j<<1|1];
	}
	for(int j=0;j<m;j++)
	{
		string tmp(n,0);
		for(int i=0;i<n;i++) tmp[i]=a[i][j];
		auto res=manacher(tmp);
		for(int i=0;i+1<n;i++) Cr[i][j]=res[i<<1|1];
	}
}
bool fl[1000005],fr[1000005],fu[1000005],fd[1000005];
void check()
{
	static int tmp[1000005];
	fill(fl,fl+n,false),fill(fr,fr+n,false);
	fill(fu,fu+m,false),fill(fd,fd+m,false);
	fl[0]=true,tmp[0]=1;
	for(int i=1;i<n;i++)
	{
		int R=INF;
		for(int j=0;j<m;j++) R=min(R,Cr[i-1][j]);
		tmp[i]=tmp[i-1];
		if(tmp[i-1]-tmp[i-R]+fl[i-R]) fl[i]=true;
		tmp[i]+=fl[i];
	}
	fr[n-1]=true,tmp[n-1]=1;
	for(int i=n-2;~i;i--)
	{
		int R=INF;
		for(int j=0;j<m;j++) R=min(R,Cr[i][j]);
		tmp[i]=tmp[i+1];
		if(tmp[i+1]-tmp[i+R]+fr[i+R]) fr[i]=true;
		tmp[i]+=fr[i];
	}
	fu[0]=true,tmp[0]=1;
	for(int j=1;j<m;j++)
	{
		int R=INF;
		for(int i=0;i<n;i++) R=min(R,Rr[i][j-1]);
		tmp[j]=tmp[j-1];
		if(tmp[j-1]-tmp[j-R]+fu[j-R]) fu[j]=true;
		tmp[j]+=fu[j];
	}
	fd[m-1]=true,tmp[m-1]=1;
	for(int j=m-2;~j;j--)
	{
		int R=INF;
		for(int i=0;i<n;i++) R=min(R,Rr[i][j]);
		tmp[j]=tmp[j+1];
		if(tmp[j+1]-tmp[j+R]+fd[j+R]) fd[j]=true;
		tmp[j]+=fd[j];
	}
}
constexpr int dirs[4][2]={{0,1},{0,-1},{-1,0},{1,0}};
vector<int> lnxt,unxt;
int fa[1000005],mnx[1000005],mxx[1000005],mny[1000005],mxy[1000005];
inline int findFa(int x) { return x!=fa[x]?fa[x]=findFa(fa[x]):x; }
inline void merge(int x,int y)
{
	x=findFa(x),y=findFa(y);
	if(x==y) return;
	mnx[x]=min(mnx[x],mnx[y]),mxx[x]=max(mxx[x],mxx[y]);
	mny[x]=min(mny[x],mny[y]),mxy[x]=max(mxy[x],mxy[y]);
	fa[y]=x;
}
void prework()
{
	lnxt=vector(n,0),lnxt[n-1]=n-1;
	for(int i=n-2;~i;i--) lnxt[i]=(fr[i]?i:lnxt[i+1]);
	unxt=vector(m,0),unxt[m-1]=m-1;
	for(int i=m-2;~i;i--) unxt[i]=(fd[i]?i:unxt[i+1]);
	iota(fa,fa+n*m,0);
	for(int i=0;i<n;i++) for(int j=0;j<m;j++)
	{
		int id=i*m+j;
		mnx[id]=mxx[id]=i;
		mny[id]=mxy[id]=j;
	}
	for(int i=0;i<n;i++) for(int j=0;j<m;j++)
	{
		if(a[i][j]!='0') continue;
		for(auto &[dx,dy]: dirs)
		{
			int x=i+dx,y=j+dy;
			if(x<0 || x>=n || y<0 || y>=m) continue;
			if(a[x][y]!='0') continue;
			merge(i*m+j,x*m+y);
		}
	}
}
struct Rect
{
	int l,r,u,d,id;
	Rect()=default;
	Rect(int _l,int _r,int _u,int _d,int _i=0): l(_l),r(_r),u(_u),d(_d),id(_i){}
};
vector<Rect> q;
UI tot,sum[1000005];
void solve(int X,int Y,int sym)
{
	vector s(n,vector(m,0u));
	for(auto [l,r,u,d,id]: q) if(!id)
	{
		r-=X,d-=Y;
		if(l>r || u>d) continue;
		s[l][u]++;
		if(r+1<n) s[r+1][u]--;
		if(d+1<m) s[l][d+1]--;
		if(r+1<n && d+1<m) s[r+1][d+1]++;
	}
	for(int i=0;i<n;i++) for(int j=0;j<m;j++)
	{
		if(i) s[i][j]+=s[i-1][j];
		if(j) s[i][j]+=s[i][j-1];
		if(i && j) s[i][j]-=s[i-1][j-1];
	}
	for(int i=0;i<n;i++) for(int j=0;j<m;j++)
	{
		if(i) s[i][j]+=s[i-1][j];
		if(j) s[i][j]+=s[i][j-1];
		if(i && j) s[i][j]-=s[i-1][j-1];
	}
	for(auto [l,r,u,d,id]: q) if(id)
	{
		r-=X,d-=Y;
		if(l>r || u>d) continue;
		sum[id]+=sym*s[r][d];
		if(l) sum[id]-=sym*s[l-1][d];
		if(u) sum[id]-=sym*s[r][u-1];
		if(l && u) sum[id]+=sym*s[l-1][u-1];
	}
}
int main()
{
	qin>>T;
	while(T--)
	{
		qin>>n>>m;
		a=vector(n,string(m,0));
		for(int i=0;i<n;i++) qin>>a[i];
		getR();
		check();
		prework();
		q.clear(),tot=0;
		for(int i=0,id=0;i<n;i++) for(int j=0;j<m;j++,id++)
			if(a[i][j]=='0' && findFa(id)==id)
				q.emplace_back(mnx[id],mxx[id],mny[id],mxy[id]);
		for(int i=0;i<n;i++) for(int j=0;j<m;j++)
			if(fl[i] && fu[j] && lnxt[i]<n && unxt[j]<m)
				sum[++tot]=0,q.emplace_back(i,lnxt[i],j,unxt[j],tot);
		solve(0,0,1);
		solve(0,1,-1);
		solve(1,0,-1);
		solve(1,1,1);
		qout<<*max_element(sum+1,sum+tot+1)<<'\n';
	}
	return 0;
}
/*
3
2 5
11001
11001
5 7
1001100
0110011
0101101
0010010
1000000
3 2
11
11
11

*/